示例#1
0
GLOBAL void UMF_assemble
#else
GLOBAL void UMF_assemble_fixq
#endif
(
    NumericType *Numeric,
    WorkType *Work
)
{
    /* ---------------------------------------------------------------------- */
    /* local variables */
    /* ---------------------------------------------------------------------- */

    Int e, i, row, col, i2, nrows, ncols, f, tpi, extcdeg, extrdeg, rdeg0,
	cdeg0, son_list, next, nrows_to_assemble,
	ncols_to_assemble, ngetrows, j, j2,
	nrowsleft,	/* number of rows remaining in S */
	ncolsleft,	/* number of columns remaining in S */
	prior_Lson, prior_Uson, *E, *Cols, *Rows, *Wm, *Woo,
	*Row_tuples, *Row_degree, *Row_tlen,
	*Col_tuples, *Col_tlen ;
    Unit *Memory, *p ;
    Element *ep ;
    Tuple *tp, *tp1, *tp2, *tpend ;
    Entry
	*S,		/* a pointer into the contribution block of a son */
	*Fcblock,	/* current contribution block */
	*Fcol ;		/* a column of FC */
    Int *Frpos,
	*Fcpos,
	fnrows,		/* number of rows in contribution block in F */
	fncols ;	/* number of columns in contribution block in F */

#if !defined (FIXQ) || !defined (NDEBUG)
    Int *Col_degree ;
#endif

#ifndef NDEBUG
    Int n_row, n_col ;
    n_row = Work->n_row ;
    n_col = Work->n_col ;
    DEBUG3 (("::Assemble SCANS 1-4\n")) ;
    UMF_dump_current_front (Numeric, Work, TRUE) ;
#endif

#if !defined (FIXQ) || !defined (NDEBUG)
    Col_degree = Numeric->Cperm ;   /* not updated if FIXQ is true */
#endif

    /* ---------------------------------------------------------------------- */
    /* get parameters */
    /* ---------------------------------------------------------------------- */

    fncols = Work->fncols ;
    fnrows = Work->fnrows ;
    Fcpos = Work->Fcpos ;
    Frpos = Work->Frpos ;
    Row_degree = Numeric->Rperm ;
    Row_tuples = Numeric->Uip ;
    Row_tlen   = Numeric->Uilen ;
    Col_tuples = Numeric->Lip ;
    Col_tlen   = Numeric->Lilen ;
    E = Work->E ;
    Memory = Numeric->Memory ;
    Wm = Work->Wm ;
    Woo = Work->Woo ;
    rdeg0 = Work->rdeg0 ;
    cdeg0 = Work->cdeg0 ;

#ifndef NDEBUG
    DEBUG6 (("============================================\n")) ;
    DEBUG6 (("Degree update, assembly.\n")) ;
    DEBUG6 (("pivot row pattern:  fncols="ID"\n", fncols)) ;
    for (j = 0 ; j < fncols ; j++)
    {
	col = Work->Fcols [j] ;
	DEBUG6 ((ID" ", col)) ;
	ASSERT (Fcpos [col] == j * Work->fnr_curr) ;
	ASSERT (NON_PIVOTAL_COL (col)) ;
    }
    ASSERT (Fcpos [Work->pivcol] >= 0) ;
    DEBUG6 (("pivcol: "ID" pos "ID" fnr_curr "ID" fncols "ID"\n",
	Work->pivcol, Fcpos [Work->pivcol], Work->fnr_curr, fncols)) ;
    ASSERT (Fcpos [Work->pivcol] <  fncols * Work->fnr_curr) ;
    DEBUG6 (("\npivot col pattern:  fnrows="ID"\n", fnrows)) ;
    for (i = 0 ; i < fnrows ; i++)
    {
	row = Work->Frows [i] ;
	DEBUG6 ((ID" ", row)) ;
	ASSERT (Frpos [row] == i) ;
	ASSERT (NON_PIVOTAL_ROW (row)) ;
    }
    DEBUG6 (("\n")) ;
    ASSERT (Frpos [Work->pivrow] >= 0) ;
    ASSERT (Frpos [Work->pivrow] < fnrows) ;
    ASSERT (Work->Flublock == (Entry *) (Numeric->Memory + E [0])) ;
    ASSERT (Work->Fcblock == Work->Flublock + Work->nb *
	(Work->nb + Work->fnr_curr + Work->fnc_curr)) ;
#endif

    Fcblock = Work->Fcblock ;

    /* ---------------------------------------------------------------------- */
    /* determine the largest actual frontal matrix size (for Info only) */
    /* ---------------------------------------------------------------------- */

    ASSERT (fnrows == Work->fnrows_new + 1) ;
    ASSERT (fncols == Work->fncols_new + 1) ;

    Numeric->maxnrows = MAX (Numeric->maxnrows, fnrows) ;
    Numeric->maxncols = MAX (Numeric->maxncols, fncols) ;

    /* this is safe from integer overflow, since the current frontal matrix
     * is already allocated. */
    Numeric->maxfrsize = MAX (Numeric->maxfrsize, fnrows * fncols) ;

    /* ---------------------------------------------------------------------- */
    /* assemble from prior elements into the current frontal matrix */
    /* ---------------------------------------------------------------------- */

    DEBUG2 (("New assemble start [prior_element:"ID"\n", Work->prior_element)) ;

    /* Currently no rows or columns are marked.  No elements are scanned, */
    /* that is, (ep->next == EMPTY) is true for all elements */

    son_list = 0 ;	/* start creating son_list [ */

    /* ---------------------------------------------------------------------- */
    /* determine if most recent element is Lson or Uson of current front */
    /* ---------------------------------------------------------------------- */

    if (!Work->do_extend)
    {
	prior_Uson = ( Work->pivcol_in_front && !Work->pivrow_in_front) ;
	prior_Lson = (!Work->pivcol_in_front &&  Work->pivrow_in_front) ;
	if (prior_Uson || prior_Lson)
	{
	    e = Work->prior_element ;
	    if (e != EMPTY)
	    {
		ASSERT (E [e]) ;
		p = Memory + E [e] ;
		ep = (Element *) p ;
		ep->next = son_list ;
		son_list = e ;
#ifndef NDEBUG
		DEBUG2 (("e "ID" is Prior son "ID" "ID"\n",
		    e, prior_Uson, prior_Lson)) ;
		UMF_dump_element (Numeric, Work, e, FALSE) ;
#endif
		ASSERT (E [e]) ;
	    }
	}
    }
    Work->prior_element = EMPTY ;

    /* ---------------------------------------------------------------------- */
    /* SCAN1-row:  scan the element lists of each new row in the pivot col */
    /* and compute the external column degree for each frontal */
    /* ---------------------------------------------------------------------- */

    for (i2 = Work->fscan_row ; i2 < fnrows ; i2++)
    {
	/* Get a row */
	row = Work->NewRows [i2] ;
	if (row < 0) row = FLIP (row) ;
	ASSERT (row >= 0 && row < n_row) ;

	DEBUG6 (("SCAN1-row: "ID"\n", row)) ;
#ifndef NDEBUG
	UMF_dump_rowcol (0, Numeric, Work, row, FALSE) ;
#endif

	ASSERT (NON_PIVOTAL_ROW (row)) ;
	tpi = Row_tuples [row] ;
	if (!tpi) continue ;
	tp = (Tuple *) (Memory + tpi) ;
	tp1 = tp ;
	tp2 = tp ;
	tpend = tp + Row_tlen [row] ;
	for ( ; tp < tpend ; tp++)
	{
	    e = tp->e ;
	    ASSERT (e > 0 && e <= Work->nel) ;
	    if (!E [e]) continue ;	/* element already deallocated */
	    f = tp->f ;
	    p = Memory + E [e] ;
	    ep = (Element *) p ;
	    p += UNITS (Element, 1) ;
	    Rows = ((Int *) p) + ep->ncols ;
	    if (Rows [f] == EMPTY) continue ;	/* row already assembled */
	    ASSERT (row == Rows [f]) ;

	    if (ep->cdeg < cdeg0)
	    {
		/* first time seen in scan1-row */
		ep->cdeg = ep->nrowsleft + cdeg0 ;
		DEBUG6 (("e "ID" First seen: cdeg: "ID" ", e, ep->cdeg-cdeg0)) ;
		ASSERT (ep->ncolsleft > 0 && ep->nrowsleft > 0) ;
	    }

	    ep->cdeg-- ;	/* decrement external column degree */
	    DEBUG6 (("e "ID" New ext col deg: "ID"\n", e, ep->cdeg - cdeg0)) ;

	    /* this element is not yet in the new son list */
	    if (ep->cdeg == cdeg0 && ep->next == EMPTY)
	    {
		/* A new LUson or Uson has been found */
		ep->next = son_list ;
		son_list = e ;
	    }

	    ASSERT (ep->cdeg >= cdeg0) ;
	    *tp2++ = *tp ;	/* leave the tuple in the list */
	}
	Row_tlen [row] = tp2 - tp1 ;
    }

    /* ---------------------------------------------------------------------- */
    /* SCAN1-col:  scan the element lists of each new col in the pivot row */
    /*	 and compute the external row degree for each frontal */
    /* ---------------------------------------------------------------------- */

    for (j2 = Work->fscan_col ; j2 < fncols ; j2++)
    {
	/* Get a column */
	col = Work->NewCols [j2] ;
	if (col < 0) col = FLIP (col) ;
	ASSERT (col >= 0 && col < n_col) ;

	DEBUG6 (("SCAN 1-col: "ID"\n", col)) ;
#ifndef NDEBUG
	UMF_dump_rowcol (1, Numeric, Work, col, FALSE) ;
#endif

	ASSERT (NON_PIVOTAL_COL (col)) ;
	tpi = Col_tuples [col] ;
	if (!tpi) continue ;
	tp = (Tuple *) (Memory + tpi) ;
	tp1 = tp ;
	tp2 = tp ;
	tpend = tp + Col_tlen [col] ;
	for ( ; tp < tpend ; tp++)
	{
	    e = tp->e ;
	    ASSERT (e > 0 && e <= Work->nel) ;
	    if (!E [e]) continue ;	/* element already deallocated */
	    f = tp->f ;
	    p = Memory + E [e] ;
	    ep = (Element *) p ;
	    p += UNITS (Element, 1) ;
	    Cols = (Int *) p ;
	    if (Cols [f] == EMPTY) continue ;	/* column already assembled */
	    ASSERT (col == Cols [f]) ;

	    if (ep->rdeg < rdeg0)
	    {
		/* first time seen in scan1-col */
		ep->rdeg = ep->ncolsleft + rdeg0 ;
		DEBUG6 (("e "ID" First seen: rdeg: "ID" ", e, ep->rdeg-rdeg0)) ;
		ASSERT (ep->ncolsleft > 0 && ep->nrowsleft > 0) ;
	    }

	    ep->rdeg-- ;	/* decrement external row degree */
	    DEBUG6 (("e "ID" New ext row degree: "ID"\n", e, ep->rdeg-rdeg0)) ;

	    if (ep->rdeg == rdeg0 && ep->next == EMPTY)
	    {
		/* A new LUson or Lson has been found */
		ep->next = son_list ;
		son_list = e ;
	    }

	    ASSERT (ep->rdeg >= rdeg0) ;
	    *tp2++ = *tp ;	/* leave the tuple in the list */
	}
	Col_tlen [col] = tp2 - tp1 ;
    }

    /* ---------------------------------------------------------------------- */
    /* assemble new sons via full scans */
    /* ---------------------------------------------------------------------- */

    next = EMPTY ;

    for (e = son_list ; e > 0 ; e = next)
    {
	ASSERT (e > 0 && e <= Work->nel && E [e]) ;
	p = Memory + E [e] ;
	DEBUG2 (("New son: "ID"\n", e)) ;
#ifndef NDEBUG
	UMF_dump_element (Numeric, Work, e, FALSE) ;
#endif
	GET_ELEMENT (ep, p, Cols, Rows, ncols, nrows, S) ;
	nrowsleft = ep->nrowsleft ;
	ncolsleft = ep->ncolsleft ;
	next = ep->next ;
	ep->next = EMPTY ;

	extrdeg = (ep->rdeg < rdeg0) ? ncolsleft : (ep->rdeg - rdeg0) ;
	extcdeg = (ep->cdeg < cdeg0) ? nrowsleft : (ep->cdeg - cdeg0) ;
	ncols_to_assemble = ncolsleft - extrdeg ;
	nrows_to_assemble = nrowsleft - extcdeg ;
	DEBUG2 (("extrdeg "ID" extcdeg "ID"\n", extrdeg, extcdeg)) ;

	if (extrdeg == 0 && extcdeg == 0)
	{

	    /* -------------------------------------------------------------- */
	    /* this is an LUson - assemble an entire contribution block */
	    /* -------------------------------------------------------------- */

	    DEBUG6 (("LUson found: "ID"\n", e)) ;

	    if (nrows == nrowsleft)
	    {
		/* ---------------------------------------------------------- */
		/* no rows assembled out of this LUson yet */
		/* ---------------------------------------------------------- */

		/* compute the compressed column offset vector*/
		/* [ use Wm [0..nrows-1] for offsets */
#pragma ivdep
		for (i = 0 ; i < nrows ; i++)
		{
		    row = Rows [i] ;
		    Row_degree [row] -= ncolsleft ;
		    Wm [i] = Frpos [row] ;
		}

		if (ncols == ncolsleft)
		{
		    /* ------------------------------------------------------ */
		    /* no rows or cols assembled out of LUson yet */
		    /* ------------------------------------------------------ */

		    for (j = 0 ; j < ncols ; j++)
		    {
			col = Cols [j] ;
#ifndef FIXQ
			Col_degree [col] -= nrowsleft ;
#endif
			Fcol = Fcblock + Fcpos [col] ;
#pragma ivdep
			for (i = 0 ; i < nrows ; i++)
			{
			    /* Fcol [Wm [i]] += S [i] ; */
			    ASSEMBLE (Fcol [Wm [i]], S [i]) ;
			}
			S += nrows ;
		    }


		}
		else
		{
		    /* ------------------------------------------------------ */
		    /* only cols have been assembled out of LUson */
		    /* ------------------------------------------------------ */

		    for (j = 0 ; j < ncols ; j++)
		    {
			col = Cols [j] ;
			if (col >= 0)
			{
#ifndef FIXQ
			    Col_degree [col] -= nrowsleft ;
#endif
			    Fcol = Fcblock + Fcpos [col] ;
#pragma ivdep
			    for (i = 0 ; i < nrows ; i++)
			    {
				/* Fcol [Wm [i]] += S [i] ; */
				ASSEMBLE (Fcol [Wm [i]], S [i]) ;
			    }
			}
			S += nrows ;
		    }

		}
		/* ] done using Wm [0..nrows-1] for offsets */
	    }
	    else
	    {
		/* ---------------------------------------------------------- */
		/* some rows have been assembled out of this LUson */
		/* ---------------------------------------------------------- */

		/* compute the compressed column offset vector*/
		/* [ use Woo,Wm [0..nrowsleft-1] for offsets */
		ngetrows = 0 ;
		for (i = 0 ; i < nrows ; i++)
		{
		    row = Rows [i] ;
		    if (row >= 0)
		    {
			Row_degree [row] -= ncolsleft ;
			Woo [ngetrows] = i ;
			Wm [ngetrows++] = Frpos [row] ;
		    }
		}
		ASSERT (ngetrows == nrowsleft) ;

		if (ncols == ncolsleft)
		{
		    /* ------------------------------------------------------ */
		    /* only rows have been assembled out of this LUson */
		    /* ------------------------------------------------------ */

		    for (j = 0 ; j < ncols ; j++)
		    {
			col = Cols [j] ;
#ifndef FIXQ
			Col_degree [col] -= nrowsleft ;
#endif
			Fcol = Fcblock + Fcpos [col] ;
#pragma ivdep
			for (i = 0 ; i < nrowsleft ; i++)
			{
			    /* Fcol [Wm [i]] += S [Woo [i]] ; */
			    ASSEMBLE (Fcol [Wm [i]], S [Woo [i]]) ;
			}
			S += nrows ;
		    }

		}
		else
		{
		    /* ------------------------------------------------------ */
		    /* both rows and columns have been assembled out of LUson */
		    /* ------------------------------------------------------ */

		    for (j = 0 ; j < ncols ; j++)
		    {
			col = Cols [j] ;
			if (col >= 0)
			{
#ifndef FIXQ
			    Col_degree [col] -= nrowsleft ;
#endif
			    Fcol = Fcblock + Fcpos [col] ;
#pragma ivdep
			    for (i = 0 ; i < nrowsleft ; i++)
			    {
				/* Fcol [Wm [i]] += S [Woo [i]] ; */
				ASSEMBLE (Fcol [Wm [i]], S [Woo [i]]) ;
			    }
			}
			S += nrows ;
		    }

		}
		/* ] done using Woo,Wm [0..nrowsleft-1] */
	    }

	    /* deallocate the element: remove from ordered list */
	    UMF_mem_free_tail_block (Numeric, E [e]) ;
	    E [e] = 0 ;

	}
	else if (extcdeg == 0)
	{

	    /* -------------------------------------------------------------- */
	    /* this is a Uson - assemble all possible columns */
	    /* -------------------------------------------------------------- */

	    DEBUG6 (("New USON: "ID"\n", e)) ;
	    ASSERT (extrdeg > 0) ;

	    DEBUG6 (("New uson "ID" cols to do "ID"\n", e, ncols_to_assemble)) ;

	    if (ncols_to_assemble > 0)
	    {

		Int skip = FALSE ;
		if (ncols_to_assemble * 16 < ncols && nrows == 1)
		{
		    /* this is a tall and thin frontal matrix consisting of
		     * only one column (most likely an original column). Do
		     * not assemble it.   It cannot be the pivot column, since
		     * the pivot column element would be an LU son, not an Lson,
		     * of the current frontal matrix. */
		    ASSERT (nrowsleft == 1) ;
		    ASSERT (Rows [0] >= 0 && Rows [0] < Work->n_row) ;
		    skip = TRUE ;
		    Work->any_skip = TRUE ;
		}

		if (!skip)
		{

		    if (nrows == nrowsleft)
		    {
			/* -------------------------------------------------- */
			/* no rows have been assembled out of this Uson yet */
			/* -------------------------------------------------- */

			/* compute the compressed column offset vector */
			/* [ use Wm [0..nrows-1] for offsets */
#pragma ivdep
			for (i = 0 ; i < nrows ; i++)
			{
			    row = Rows [i] ;
			    ASSERT (row >= 0 && row < n_row) ;
			    Row_degree [row] -= ncols_to_assemble ;
			    Wm [i] = Frpos [row] ;
			}

			for (j = 0 ; j < ncols ; j++)
			{
			    col = Cols [j] ;
			    if ((col >= 0) && (Fcpos [col] >= 0))
			    {
#ifndef FIXQ
				Col_degree [col] -= nrowsleft ;
#endif
				Fcol = Fcblock + Fcpos [col] ;
#pragma ivdep
				for (i = 0 ; i < nrows ; i++)
				{
				    /* Fcol [Wm [i]] += S [i] ; */
				    ASSEMBLE (Fcol [Wm [i]], S [i]) ;
				}
				/* flag the column as assembled from Uson */
				Cols [j] = EMPTY ;
			    }
			    S += nrows ;
			}


			/* ] done using Wm [0..nrows-1] for offsets */
		    }
		    else
		    {
			/* -------------------------------------------------- */
			/* some rows have been assembled out of this Uson */
			/* -------------------------------------------------- */

			/* compute the compressed column offset vector*/
			/* [ use Woo,Wm [0..nrows-1] for offsets */
			ngetrows = 0 ;
			for (i = 0 ; i < nrows ; i++)
			{
			    row = Rows [i] ;
			    if (row >= 0)
			    {
				Row_degree [row] -= ncols_to_assemble ;
				ASSERT (row < n_row && Frpos [row] >= 0) ;
				Woo [ngetrows] = i ;
				Wm [ngetrows++] = Frpos [row] ;
			    }
			}
			ASSERT (ngetrows == nrowsleft) ;

			for (j = 0 ; j < ncols ; j++)
			{
			    col = Cols [j] ;
			    if ((col >= 0) && (Fcpos [col] >= 0))
			    {
#ifndef FIXQ
				Col_degree [col] -= nrowsleft ;
#endif
				Fcol = Fcblock + Fcpos [col] ;
#pragma ivdep
				for (i = 0 ; i < nrowsleft ; i++)
				{
				    /* Fcol [Wm [i]] += S [Woo [i]] ; */
				    ASSEMBLE (Fcol [Wm [i]], S [Woo [i]]) ;
				}
				/* flag the column as assembled from Uson */
				Cols [j] = EMPTY ;
			    }
			    S += nrows ;
			}

			/* ] done using Woo,Wm */
		    }
		    ep->ncolsleft = extrdeg ;
		}
	    }

	}
	else
	{

	    /* -------------------------------------------------------------- */
	    /* this is an Lson - assemble all possible rows */
	    /* -------------------------------------------------------------- */

	    DEBUG6 (("New LSON: "ID"\n", e)) ;
	    ASSERT (extrdeg == 0 && extcdeg > 0) ;

	    DEBUG6 (("New lson "ID" rows to do "ID"\n", e, nrows_to_assemble)) ;

	    if (nrows_to_assemble > 0)
	    {

		Int skip = FALSE ;
		if (nrows_to_assemble * 16 < nrows && ncols == 1)
		{
		    /* this is a tall and thin frontal matrix consisting of
		     * only one column (most likely an original column). Do
		     * not assemble it.   It cannot be the pivot column, since
		     * the pivot column element would be an LU son, not an Lson,
		     * of the current frontal matrix. */
		    ASSERT (ncolsleft == 1) ;
		    ASSERT (Cols [0] >= 0 && Cols [0] < Work->n_col) ;
		    Work->any_skip = TRUE ;
		    skip = TRUE ;
		}

		if (!skip)
		{

		    /* compute the compressed column offset vector */
		    /* [ use Woo,Wm [0..nrows-1] for offsets */
		    ngetrows = 0 ;
		    for (i = 0 ; i < nrows ; i++)
		    {
			row = Rows [i] ;
			if ((row >= 0) && (Frpos [row] >= 0))
			{
			    ASSERT (row < n_row) ;
			    Row_degree [row] -= ncolsleft ;
			    Woo [ngetrows] = i ;
			    Wm [ngetrows++] = Frpos [row] ;
			    /* flag the row as assembled from the Lson */
			    Rows [i] = EMPTY ;
			}
		    }
		    ASSERT (nrowsleft - ngetrows == extcdeg) ;
		    ASSERT (ngetrows == nrows_to_assemble) ;

		    if (ncols == ncolsleft)
		    {
			/* -------------------------------------------------- */
			/* no columns assembled out this Lson yet */
			/* -------------------------------------------------- */

			for (j = 0 ; j < ncols ; j++)
			{
			    col = Cols [j] ;
			    ASSERT (col >= 0 && col < n_col) ;
#ifndef FIXQ
			    Col_degree [col] -= nrows_to_assemble ;
#endif
			    Fcol = Fcblock + Fcpos [col] ;
#pragma ivdep
			    for (i = 0 ; i < nrows_to_assemble ; i++)
			    {
				/* Fcol [Wm [i]] += S [Woo [i]] ; */
				ASSEMBLE (Fcol [Wm [i]], S [Woo [i]]) ;
			    }
			    S += nrows ;
			}


		    }
		    else
		    {
			/* -------------------------------------------------- */
			/* some columns have been assembled out of this Lson */
			/* -------------------------------------------------- */

			for (j = 0 ; j < ncols ; j++)
			{
			    col = Cols [j] ;
			    ASSERT (col < n_col) ;
			    if (col >= 0)
			    {
#ifndef FIXQ
				Col_degree [col] -= nrows_to_assemble ;
#endif
				Fcol = Fcblock + Fcpos [col] ;
#pragma ivdep
				for (i = 0 ; i < nrows_to_assemble ; i++)
				{
				    /* Fcol [Wm [i]] += S [Woo [i]] ; */
				    ASSEMBLE (Fcol [Wm [i]], S [Woo [i]]) ;
				}
			    }
			    S += nrows ;
			}

		    }

		    /* ] done using Woo,Wm */

		    ep->nrowsleft = extcdeg ;
		}
	    }
	}
    }

    /* Note that garbage collection, and build tuples */
    /* both destroy the son list. */

    /* ] son_list now empty */

    /* ---------------------------------------------------------------------- */
    /* If frontal matrix extended, assemble old L/Usons from new rows/cols */
    /* ---------------------------------------------------------------------- */

    /* ---------------------------------------------------------------------- */
    /* SCAN2-row:  assemble rows of old Lsons from the new rows */
    /* ---------------------------------------------------------------------- */

#ifndef NDEBUG
    DEBUG7 (("Current frontal matrix: (prior to scan2-row)\n")) ;
    UMF_dump_current_front (Numeric, Work, TRUE) ;
#endif

    /* rescan the pivot row */
    if (Work->any_skip)
    {
	row_assemble (Work->pivrow, Numeric, Work) ;
    }

    if (Work->do_scan2row)
    {
	for (i2 = Work->fscan_row ; i2 < fnrows ; i2++)
	{
	    /* Get a row */
	    row = Work->NewRows [i2] ;
	    if (row < 0) row = FLIP (row) ;
	    ASSERT (row >= 0 && row < n_row) ;
	    if (!(row == Work->pivrow && Work->any_skip))
	    {
		/* assemble it */
		row_assemble (row, Numeric, Work) ;
	    }
	}
    }

    /* ---------------------------------------------------------------------- */
    /* SCAN2-col:  assemble columns of old Usons from the new columns */
    /* ---------------------------------------------------------------------- */

#ifndef NDEBUG
    DEBUG7 (("Current frontal matrix: (prior to scan2-col)\n")) ;
    UMF_dump_current_front (Numeric, Work, TRUE) ;
#endif

    /* rescan the pivot col */
    if (Work->any_skip)
    {
	col_assemble (Work->pivcol, Numeric, Work) ;
    }

    if (Work->do_scan2col)
    {

	for (j2 = Work->fscan_col ; j2 < fncols ; j2++)
	{
	    /* Get a column */
	    col = Work->NewCols [j2] ;
	    if (col < 0) col = FLIP (col) ;
	    ASSERT (col >= 0 && col < n_col) ;
	    if (!(col == Work->pivcol && Work->any_skip))
	    {
		/* assemble it */
		col_assemble (col, Numeric, Work) ;
	    }
	}
    }

    /* ---------------------------------------------------------------------- */
    /* done.  the remainder of this routine is used only when in debug mode */
    /* ---------------------------------------------------------------------- */

#ifndef NDEBUG

    /* ---------------------------------------------------------------------- */
    /* when debugging: make sure the assembly did everything that it could */
    /* ---------------------------------------------------------------------- */

    DEBUG3 (("::Assemble done\n")) ;

    for (i2 = 0 ; i2 < fnrows ; i2++)
    {
	/* Get a row */
	row = Work->Frows [i2] ;
	ASSERT (row >= 0 && row < n_row) ;

	DEBUG6 (("DEBUG SCAN 1: "ID"\n", row)) ;
	UMF_dump_rowcol (0, Numeric, Work, row, TRUE) ;

	ASSERT (NON_PIVOTAL_ROW (row)) ;
	tpi = Row_tuples [row] ;
	if (!tpi) continue ;
	tp = (Tuple *) (Memory + tpi) ;
	tpend = tp + Row_tlen [row] ;
	for ( ; tp < tpend ; tp++)
	{
	    e = tp->e ;
	    ASSERT (e > 0 && e <= Work->nel) ;
	    if (!E [e]) continue ;	/* element already deallocated */
	    f = tp->f ;
	    p = Memory + E [e] ;
	    ep = (Element *) p ;
	    p += UNITS (Element, 1) ;
	    Cols = (Int *) p ;
	    Rows = ((Int *) p) + ep->ncols ;
	    if (Rows [f] == EMPTY) continue ;	/* row already assembled */
	    ASSERT (row == Rows [f]) ;
	    extrdeg = (ep->rdeg < rdeg0) ? ep->ncolsleft : (ep->rdeg - rdeg0) ;
	    extcdeg = (ep->cdeg < cdeg0) ? ep->nrowsleft : (ep->cdeg - cdeg0) ;
	    DEBUG6 ((
		"e "ID" After assembly ext row deg: "ID" ext col degree "ID"\n",
		e, extrdeg, extcdeg)) ;

	    if (Work->any_skip)
	    {
		/* no Lsons in any row, except for very tall and thin ones */
		ASSERT (extrdeg >= 0) ;
		if (extrdeg == 0)
		{
		    /* this is an unassemble Lson */
		    ASSERT (ep->ncols == 1) ;
		    ASSERT (ep->ncolsleft == 1) ;
		    col = Cols [0] ;
		    ASSERT (col != Work->pivcol) ;
		}
	    }
	    else
	    {
		/* no Lsons in any row */
		ASSERT (extrdeg > 0) ;
		/* Uson external row degree is = number of cols left */
		ASSERT (IMPLIES (extcdeg == 0, extrdeg == ep->ncolsleft)) ;
	    }
	}
    }

    /* ---------------------------------------------------------------------- */

    for (j2 = 0 ; j2 < fncols ; j2++)
    {
	/* Get a column */
	col = Work->Fcols [j2] ;
	ASSERT (col >= 0 && col < n_col) ;

	DEBUG6 (("DEBUG SCAN 2: "ID"\n", col)) ;
#ifndef FIXQ
	UMF_dump_rowcol (1, Numeric, Work, col, TRUE) ;
#else
	UMF_dump_rowcol (1, Numeric, Work, col, FALSE) ;
#endif

	ASSERT (NON_PIVOTAL_COL (col)) ;
	tpi = Col_tuples [col] ;
	if (!tpi) continue ;
	tp = (Tuple *) (Memory + tpi) ;
	tpend = tp + Col_tlen [col] ;
	for ( ; tp < tpend ; tp++)
	{
	    e = tp->e ;
	    ASSERT (e > 0 && e <= Work->nel) ;
	    if (!E [e]) continue ;	/* element already deallocated */
	    f = tp->f ;
	    p = Memory + E [e] ;
	    ep = (Element *) p ;
	    p += UNITS (Element, 1) ;
	    Cols = (Int *) p ;
	    Rows = ((Int *) p) + ep->ncols ;
	    if (Cols [f] == EMPTY) continue ;	/* column already assembled */
	    ASSERT (col == Cols [f]) ;
	    extrdeg = (ep->rdeg < rdeg0) ? ep->ncolsleft : (ep->rdeg - rdeg0) ;
	    extcdeg = (ep->cdeg < cdeg0) ? ep->nrowsleft : (ep->cdeg - cdeg0) ;
	    DEBUG6 (("e "ID" After assembly ext col deg: "ID"\n", e, extcdeg)) ;

	    if (Work->any_skip)
	    {
		/* no Usons in any column, except for very tall and thin ones */
		ASSERT (extcdeg >= 0) ;
		if (extcdeg == 0)
		{
		    /* this is an unassemble Uson */
		    ASSERT (ep->nrows == 1) ;
		    ASSERT (ep->nrowsleft == 1) ;
		    row = Rows [0] ;
		    ASSERT (row != Work->pivrow) ;
		}
	    }
	    else
	    {
		/* no Usons in any column */
		ASSERT (extcdeg > 0) ;
		/* Lson external column degree is = number of rows left */
		ASSERT (IMPLIES (extrdeg == 0, extcdeg == ep->nrowsleft)) ;
	    }
	}
    }
#endif /* NDEBUG */
}
示例#2
0
GLOBAL Int UMF_build_tuples
(
    NumericType *Numeric,
    WorkType *Work
)
{
    /* ---------------------------------------------------------------------- */
    /* local variables */
    /* ---------------------------------------------------------------------- */

    Int e, nrows, ncols, nel, *Rows, *Cols, row, col, n_row, n_col, *E,
	*Row_tuples, *Row_degree, *Row_tlen,
	*Col_tuples, *Col_degree, *Col_tlen, n1 ;
    Element *ep ;
    Unit *p ;
    Tuple tuple, *tp ;

    /* ---------------------------------------------------------------------- */
    /* get parameters */
    /* ---------------------------------------------------------------------- */

    E = Work->E ;
    Col_degree = Numeric->Cperm ;	/* for NON_PIVOTAL_COL macro */
    Row_degree = Numeric->Rperm ;	/* for NON_PIVOTAL_ROW macro */
    Row_tuples = Numeric->Uip ;
    Row_tlen   = Numeric->Uilen ;
    Col_tuples = Numeric->Lip ;
    Col_tlen   = Numeric->Lilen ;
    n_row = Work->n_row ;
    n_col = Work->n_col ;
    nel = Work->nel ;
    n1 = Work->n1 ;

    DEBUG3 (("BUILD_TUPLES: n_row "ID" n_col "ID" nel "ID"\n",
	n_row, n_col, nel)) ;

    /* ---------------------------------------------------------------------- */
    /* allocate space for the tuple lists */
    /* ---------------------------------------------------------------------- */

    /* Garbage collection and memory reallocation have already attempted to */
    /* ensure that there is enough memory for all the tuple lists.  If */
    /* memory allocation fails here, then there is nothing more to be done. */

    for (row = n1 ; row < n_row ; row++)
    {
	if (NON_PIVOTAL_ROW (row))
	{
	    Row_tuples [row] = UMF_mem_alloc_tail_block (Numeric,
		UNITS (Tuple, TUPLES (Row_tlen [row]))) ;
	    if (!Row_tuples [row])
	    {
		/* :: out of memory for row tuples :: */
		DEBUGm4 (("out of memory: build row tuples\n")) ;
		return (FALSE) ;	/* out of memory for row tuples */
	    }
	    Row_tlen [row] = 0 ;
	}
    }

    /* push on stack in reverse order, so column tuples are in the order */
    /* that they will be deleted. */
    for (col = n_col-1 ; col >= n1 ; col--)
    {
	if (NON_PIVOTAL_COL (col))
	{
	    Col_tuples [col] = UMF_mem_alloc_tail_block (Numeric,
		UNITS (Tuple, TUPLES (Col_tlen [col]))) ;
	    if (!Col_tuples [col])
	    {
		/* :: out of memory for col tuples :: */
		DEBUGm4 (("out of memory: build col tuples\n")) ;
		return (FALSE) ;	/* out of memory for col tuples */
	    }
	    Col_tlen [col] = 0 ;
	}
    }

#ifndef NDEBUG
    UMF_dump_memory (Numeric) ;
#endif

    /* ---------------------------------------------------------------------- */
    /* create the tuple lists (exclude element 0) */
    /* ---------------------------------------------------------------------- */

    /* for all elements, in order of creation */
    for (e = 1 ; e <= nel ; e++)
    {
	DEBUG9 (("Adding tuples for element: "ID" at "ID"\n", e, E [e])) ;
	ASSERT (E [e]) ;	/* no external fragmentation */
	p = Numeric->Memory + E [e] ;
	GET_ELEMENT_PATTERN (ep, p, Cols, Rows, ncols) ;
	nrows = ep->nrows ;
	ASSERT (e != 0) ;
	ASSERT (e == 0 || nrows == ep->nrowsleft) ;
	ASSERT (e == 0 || ncols == ep->ncolsleft) ;
	tuple.e = e ;
	for (tuple.f = 0 ; tuple.f < ncols ; tuple.f++)
	{
	    col = Cols [tuple.f] ;
	    ASSERT (col >= n1 && col < n_col) ;
	    ASSERT (NON_PIVOTAL_COL (col)) ;
	    ASSERT (Col_tuples [col]) ;
	    tp = ((Tuple *) (Numeric->Memory + Col_tuples [col]))
		+ Col_tlen [col]++ ;
	    *tp = tuple ;
#ifndef NDEBUG
	    UMF_dump_rowcol (1, Numeric, Work, col, FALSE) ;
#endif
	}
	for (tuple.f = 0 ; tuple.f < nrows ; tuple.f++)
	{
	    row = Rows [tuple.f] ;
	    ASSERT (row >= n1 && row < n_row) ;
	    ASSERT (NON_PIVOTAL_COL (col)) ;
	    ASSERT (Row_tuples [row]) ;
	    tp = ((Tuple *) (Numeric->Memory + Row_tuples [row]))
		+ Row_tlen [row]++ ;
	    *tp = tuple ;
#ifndef NDEBUG
	    UMF_dump_rowcol (0, Numeric, Work, row, FALSE) ;
#endif
	}
    }

    /* ---------------------------------------------------------------------- */
    /* the tuple lists are now valid, and can be scanned */
    /* ---------------------------------------------------------------------- */

#ifndef NDEBUG
    UMF_dump_memory (Numeric) ;
    UMF_dump_matrix (Numeric, Work, FALSE) ;
#endif
    DEBUG3 (("BUILD_TUPLES: done\n")) ;
    return (TRUE) ;
}
示例#3
0
PRIVATE void row_assemble
(
    Int row,
    NumericType *Numeric,
    WorkType *Work
)
{

    Entry *S, *Fcblock, *Frow ;
    Int tpi, e, *E, *Fcpos, *Frpos, *Row_degree, *Row_tuples, *Row_tlen, rdeg0,
	f, nrows, ncols, *Rows, *Cols, col, ncolsleft, j ;
    Tuple *tp, *tp1, *tp2, *tpend ;
    Unit *Memory, *p ;
    Element *ep ;

#ifndef FIXQ
    Int *Col_degree ;
    Col_degree = Numeric->Cperm ;
#endif

    Row_tuples = Numeric->Uip ;
    tpi = Row_tuples [row] ;
    if (!tpi) return ;

    Memory = Numeric->Memory ;
    E = Work->E ;
    Fcpos = Work->Fcpos ;
    Frpos = Work->Frpos ;
    Row_degree = Numeric->Rperm ;
    Row_tlen   = Numeric->Uilen ;
    E = Work->E ;
    Memory = Numeric->Memory ;
    rdeg0 = Work->rdeg0 ;
    Fcblock = Work->Fcblock ;

#ifndef NDEBUG
    DEBUG6 (("SCAN2-row: "ID"\n", row)) ;
    UMF_dump_rowcol (0, Numeric, Work, row, FALSE) ;
#endif

    ASSERT (NON_PIVOTAL_ROW (row)) ;

    tp = (Tuple *) (Memory + tpi) ;
    tp1 = tp ;
    tp2 = tp ;
    tpend = tp + Row_tlen [row] ;
    for ( ; tp < tpend ; tp++)
    {
	e = tp->e ;
	ASSERT (e > 0 && e <= Work->nel) ;
	if (!E [e]) continue ;	/* element already deallocated */
	f = tp->f ;
	p = Memory + E [e] ;
	ep = (Element *) p ;
	p += UNITS (Element, 1) ;
	Cols = (Int *) p ;
	Rows = Cols + ep->ncols ;
	if (Rows [f] == EMPTY) continue ;   /* row already assembled */
	ASSERT (row == Rows [f] && row >= 0 && row < Work->n_row) ;

	if (ep->rdeg == rdeg0)
	{
	    /* ------------------------------------------------------ */
	    /* this is an old Lson - assemble just one row */
	    /* ------------------------------------------------------ */

	    /* flag the row as assembled from the Lson */
	    Rows [f] = EMPTY ;

	    nrows = ep->nrows ;
	    ncols = ep->ncols ;

	    p += UNITS (Int, ncols + nrows) ;
	    S = ((Entry *) p) + f ;

	    DEBUG6 (("Old LSON: "ID"\n", e)) ;
#ifndef NDEBUG
	    UMF_dump_element (Numeric, Work, e, FALSE) ;
#endif

	    ncolsleft = ep->ncolsleft ;

	    Frow = Fcblock + Frpos [row] ;
	    DEBUG6 (("LSON found (in scan2-row): "ID"\n", e)) ;

	    Row_degree [row] -= ncolsleft ;

	    if (ncols == ncolsleft)
	    {
		/* -------------------------------------------------- */
		/* no columns assembled out this Lson yet */
		/* -------------------------------------------------- */

#pragma ivdep
		for (j = 0 ; j < ncols ; j++)
		{
		    col = Cols [j] ;
		    ASSERT (col >= 0 && col < Work->n_col) ;
#ifndef FIXQ
		    Col_degree [col] -- ;
#endif
		    /* Frow [Fcpos [col]] += *S ; */
		    ASSEMBLE (Frow [Fcpos [col]], *S) ;
		    S += nrows ;
		}

	    }
	    else
	    {
		/* -------------------------------------------------- */
		/* some columns have been assembled out of this Lson */
		/* -------------------------------------------------- */

#pragma ivdep
		for (j = 0 ; j < ncols ; j++)
		{
		    col = Cols [j] ;
		    if (col >= 0)
		    {
			ASSERT (col < Work->n_col) ;
#ifndef FIXQ
			Col_degree [col] -- ;
#endif
			/* Frow [Fcpos [col]] += *S ; */
			ASSEMBLE (Frow [Fcpos [col]], *S) ;
		    }
		    S += nrows ;
		}

	    }
	    ep->nrowsleft-- ;
	    ASSERT (ep->nrowsleft > 0) ;
	}
	else
	{
	    *tp2++ = *tp ;	/* leave the tuple in the list */
	}
    }
    Row_tlen [row] = tp2 - tp1 ;

#ifndef NDEBUG
    DEBUG7 (("row assembled in scan2-row: "ID"\n", row)) ;
    UMF_dump_rowcol (0, Numeric, Work, row, FALSE) ;
    DEBUG7 (("Current frontal matrix: (scan 1b)\n")) ;
    UMF_dump_current_front (Numeric, Work, TRUE) ;
#endif
}
示例#4
0
PRIVATE void col_assemble
(
    Int col,
    NumericType *Numeric,
    WorkType *Work
)
{

    Entry *S, *Fcblock, *Fcol ;
    Int tpi, e, *E, *Fcpos, *Frpos, *Row_degree, *Col_tuples, *Col_tlen, cdeg0,
	f, nrows, ncols, *Rows, *Cols, row, nrowsleft, i ;
    Tuple *tp, *tp1, *tp2, *tpend ;
    Unit *Memory, *p ;
    Element *ep ;

#if !defined (FIXQ) || !defined (NDEBUG)
    Int *Col_degree ;
    Col_degree = Numeric->Cperm ;
#endif

    Col_tuples = Numeric->Lip ;
    tpi = Col_tuples [col] ;
    if (!tpi) return ;

    Memory = Numeric->Memory ;
    E = Work->E ;
    Fcpos = Work->Fcpos ;
    Frpos = Work->Frpos ;
    Row_degree = Numeric->Rperm ;
    Col_tlen   = Numeric->Lilen ;
    E = Work->E ;
    Memory = Numeric->Memory ;
    cdeg0 = Work->cdeg0 ;
    Fcblock = Work->Fcblock ;

    DEBUG6 (("SCAN2-col: "ID"\n", col)) ;
#ifndef NDEBUG
    UMF_dump_rowcol (1, Numeric, Work, col, FALSE) ;
#endif

    ASSERT (NON_PIVOTAL_COL (col)) ;
    tp = (Tuple *) (Memory + tpi) ;
    tp1 = tp ;
    tp2 = tp ;
    tpend = tp + Col_tlen [col] ;
    for ( ; tp < tpend ; tp++)
    {
	e = tp->e ;
	ASSERT (e > 0 && e <= Work->nel) ;
	if (!E [e]) continue ;	/* element already deallocated */
	f = tp->f ;
	p = Memory + E [e] ;
	ep = (Element *) p ;
	p += UNITS (Element, 1) ;
	Cols = (Int *) p ;

	if (Cols [f] == EMPTY) continue ;   /* col already assembled */
	ASSERT (col == Cols [f] && col >= 0 && col < Work->n_col) ;

	if (ep->cdeg == cdeg0)
	{
	    /* ------------------------------------------------------ */
	    /* this is an old Uson - assemble just one col */
	    /* ------------------------------------------------------ */

	    /* flag the col as assembled from the Uson */
	    Cols [f] = EMPTY ;

	    nrows = ep->nrows ;
	    ncols = ep->ncols ;
	    Rows = Cols + ncols ;
	    p += UNITS (Int, ncols + nrows) ;
	    S = ((Entry *) p) + f * nrows ;

	    DEBUG6 (("Old USON: "ID"\n", e)) ;
#ifndef NDEBUG
	    UMF_dump_element (Numeric, Work, e, FALSE) ;
#endif

	    nrowsleft = ep->nrowsleft ;

	    Fcol = Fcblock + Fcpos [col] ;
	    DEBUG6 (("USON found (in scan2-col): "ID"\n", e)) ;
#ifndef FIXQ
	    Col_degree [col] -= nrowsleft ;
#endif
	    if (nrows == nrowsleft)
	    {
		/* -------------------------------------------------- */
		/* no rows assembled out of this Uson yet */
		/* -------------------------------------------------- */

#pragma ivdep
		for (i = 0 ; i < nrows ; i++)
		{
		    row = Rows [i] ;
		    ASSERT (row >= 0 && row < Work->n_row) ;
		    Row_degree [row]-- ;
		    /* Fcol [Frpos [row]] += S [i] ; */
		    ASSEMBLE (Fcol [Frpos [row]], S [i]) ;
		}
	    }
	    else
	    {
		/* -------------------------------------------------- */
		/* some rows have been assembled out of this Uson */
		/* -------------------------------------------------- */

#pragma ivdep
		for (i = 0 ; i < nrows ; i++)
		{
		    row = Rows [i] ;
		    if (row >= 0)
		    {
			ASSERT (row < Work->n_row) ;
			Row_degree [row]-- ;
			/* Fcol [Frpos [row]] += S [i] ; */
			ASSEMBLE (Fcol [Frpos [row]], S [i]) ;
		    }
		}
	    }
	    ep->ncolsleft-- ;
	    ASSERT (ep->ncolsleft > 0) ;
	}
	else
	{
	    *tp2++ = *tp ;	/* leave the tuple in the list */
	}
    }
    Col_tlen [col] = tp2 - tp1 ;

#ifndef NDEBUG
    DEBUG7 (("Column assembled in scan2-col: "ID"\n", col)) ;
    UMF_dump_rowcol (1, Numeric, Work, col, FALSE) ;
    DEBUG7 (("Current frontal matrix: after scan2-col\n")) ;
    UMF_dump_current_front (Numeric, Work, TRUE) ;
#endif

}
示例#5
0
GLOBAL Int UMF_row_search
(
    NumericType *Numeric,
    WorkType *Work,
    SymbolicType *Symbolic,
    Int cdeg0,			/* length of column in Front */
    Int cdeg1,			/* length of column outside Front */
    const Int Pattern [ ],	/* pattern of column, Pattern [0..cdeg1 -1] */
    const Int Pos [ ],		/* Pos [Pattern [0..cdeg1 -1]] = 0..cdeg1 -1 */
    Int pivrow [2],		/* pivrow [IN] and pivrow [OUT] */
    Int rdeg [2],		/* rdeg [IN] and rdeg [OUT] */
    Int W_i [ ],		/* pattern of pivrow [IN], */
				/* either Fcols or Woi */
    Int W_o [ ],		/* pattern of pivrow [OUT], */
				/* either Wio or Woo */
    Int prior_pivrow [2],	/* the two other rows just scanned, if any */
    const Entry Wxy [ ],	/* numerical values Wxy [0..cdeg1-1],
				   either Wx or Wy */

    Int pivcol,			/* the candidate column being searched */
    Int freebie [ ]
)
{

    /* ---------------------------------------------------------------------- */
    /* local variables */
    /* ---------------------------------------------------------------------- */

    double maxval, toler, toler2, value, pivot [2] ;
    Int i, row, deg, col, *Frpos, fnrows, *E, j, ncols, *Cols, *Rows,
	e, f, Wrpflag, *Fcpos, fncols, tpi, max_rdeg, nans_in_col, was_offdiag,
	diag_row, prefer_diagonal, *Wrp, found, *Diagonal_map ;
    Tuple *tp, *tpend, *tp1, *tp2 ;
    Unit *Memory, *p ;
    Element *ep ;
    Int *Row_tuples, *Row_degree, *Row_tlen ;

#ifndef NDEBUG
    Int *Col_degree ;
    DEBUG2 (("Row_search:\n")) ;
    for (i = 0 ; i < cdeg1 ; i++)
    {
	row = Pattern [i] ;
	DEBUG4 (("   row: "ID"\n", row)) ;
	ASSERT (row >= 0 && row < Numeric->n_row) ;
	ASSERT (i == Pos [row]) ;
    }
    /* If row is not in Pattern [0..cdeg1-1], then Pos [row] == EMPTY */
    if (UMF_debug > 0 || Numeric->n_row < 1000)
    {
	Int cnt = cdeg1 ;
	DEBUG4 (("Scan all rows:\n")) ;
	for (row = 0 ; row < Numeric->n_row ; row++)
	{
	    if (Pos [row] < 0)
	    {
		cnt++ ;
	    }
	    else
	    {
		DEBUG4 (("   row: "ID" pos "ID"\n", row, Pos [row])) ;
	    }
	}
	ASSERT (cnt == Numeric->n_row) ;
    }
    Col_degree = Numeric->Cperm ;   /* for NON_PIVOTAL_COL macro only */
    ASSERT (pivcol >= 0 && pivcol < Work->n_col) ;
    ASSERT (NON_PIVOTAL_COL (pivcol)) ;
#endif

    pivot [IN] = 0. ;
    pivot [OUT] = 0. ;

    /* ---------------------------------------------------------------------- */
    /* get parameters */
    /* ---------------------------------------------------------------------- */

    Row_degree = Numeric->Rperm ;
    Row_tuples = Numeric->Uip ;
    Row_tlen   = Numeric->Uilen ;
    Wrp = Work->Wrp ;
    Frpos = Work->Frpos ;
    E = Work->E ;
    Memory = Numeric->Memory ;
    fnrows = Work->fnrows ;

    prefer_diagonal = Symbolic->prefer_diagonal ;
    Diagonal_map = Work->Diagonal_map ;

    if (Diagonal_map)
    {
	diag_row = Diagonal_map [pivcol] ;
	was_offdiag = diag_row < 0 ;
	if (was_offdiag)
	{
	    /* the "diagonal" entry in this column was permuted here by an
	     * earlier pivot choice.  The tighter off-diagonal tolerance will
	     * be used instead of the symmetric tolerance. */
	    diag_row = FLIP (diag_row) ;
	}
	ASSERT (diag_row >= 0 && diag_row < Numeric->n_row) ;
    }
    else
    {
	diag_row = EMPTY ;	/* unused */
	was_offdiag = EMPTY ;	/* unused */
    }

    /* pivot row degree cannot exceed max_rdeg */
    max_rdeg = Work->fncols_max ;

    /* ---------------------------------------------------------------------- */
    /* scan pivot column for candidate rows */
    /* ---------------------------------------------------------------------- */

    maxval = 0.0 ;
    nans_in_col = FALSE ;

    for (i = 0 ; i < cdeg1 ; i++)
    {
	APPROX_ABS (value, Wxy [i]) ;
	if (SCALAR_IS_NAN (value))
	{
	    nans_in_col = TRUE ;
	    maxval = value ;
	    break ;
	}
	/* This test can now ignore the NaN case: */
	maxval = MAX (maxval, value) ;
    }

    /* if maxval is zero, the matrix is numerically singular */

    toler = Numeric->relpt * maxval ;
    toler2 = Numeric->relpt2 * maxval ;
    toler2 = was_offdiag ? toler : toler2 ;

    DEBUG5 (("Row_search begins [ maxval %g toler %g %g\n",
	maxval, toler, toler2)) ;
    if (SCALAR_IS_NAN (toler) || SCALAR_IS_NAN (toler2))
    {
	nans_in_col = TRUE ;
    }

    if (!nans_in_col)
    {

	/* look for the diagonal entry, if it exists */
	found = FALSE ;
	ASSERT (!SCALAR_IS_NAN (toler)) ;

	if (prefer_diagonal)
	{
	    ASSERT (diag_row != EMPTY) ;
	    i = Pos [diag_row] ;
	    if (i >= 0)
	    {
		double a ;
		ASSERT (i < cdeg1) ;
		ASSERT (diag_row == Pattern [i]) ;

		APPROX_ABS (a, Wxy [i]) ;

		ASSERT (!SCALAR_IS_NAN (a)) ;
		ASSERT (!SCALAR_IS_NAN (toler2)) ;

		if (SCALAR_IS_NONZERO (a) && a >= toler2)
		{
		    /* found it! */
		    DEBUG3 (("Symmetric pivot: "ID" "ID"\n", pivcol, diag_row));
		    found = TRUE ;
		    if (Frpos [diag_row] >= 0 && Frpos [diag_row] < fnrows)
		    {
			pivrow [IN] = diag_row ;
			pivrow [OUT] = EMPTY ;
		    }
		    else
		    {
			pivrow [IN] = EMPTY ;
			pivrow [OUT] = diag_row ;
		    }
		}
	    }
	}

	/* either no diagonal found, or we didn't look for it */
	if (!found)
	{
	    if (cdeg0 > 0)
	    {

		/* this is a column in the front */
		for (i = 0 ; i < cdeg0 ; i++)
		{
		    double a ;
		    APPROX_ABS (a, Wxy [i]) ;
		    ASSERT (!SCALAR_IS_NAN (a)) ;
		    ASSERT (!SCALAR_IS_NAN (toler)) ;
		    if (SCALAR_IS_NONZERO (a) && a >= toler)
		    {
			row = Pattern [i] ;
			deg = Row_degree [row] ;
#ifndef NDEBUG
			DEBUG6 ((ID" candidate row "ID" deg "ID" absval %g\n",
			    i, row, deg, a)) ;
			UMF_dump_rowcol (0, Numeric, Work, row, TRUE) ;
#endif
			ASSERT (Frpos [row] >= 0 && Frpos [row] < fnrows) ;
			ASSERT (Frpos [row] == i) ;
			/* row is in the current front */
			DEBUG4 ((" in front\n")) ;
			if (deg < rdeg [IN]
			    /* break ties by picking the largest entry: */
			       || (deg == rdeg [IN] && a > pivot [IN])
			    /* break ties by picking the diagonal entry: */
			    /* || (deg == rdeg [IN] && row == diag_row) */
			   )
			{
			    /* best row in front, so far */
			    pivrow [IN] = row ;
			    rdeg [IN] = deg ;
			    pivot [IN] = a ;
			}
		    }
		}
		for ( ; i < cdeg1 ; i++)
		{
		    double a ;
		    APPROX_ABS (a, Wxy [i]) ;
		    ASSERT (!SCALAR_IS_NAN (a)) ;
		    ASSERT (!SCALAR_IS_NAN (toler)) ;
		    if (SCALAR_IS_NONZERO (a) && a >= toler)
		    {
			row = Pattern [i] ;
			deg = Row_degree [row] ;
#ifndef NDEBUG
			DEBUG6 ((ID" candidate row "ID" deg "ID" absval %g\n",
			    i, row, deg, a)) ;
			UMF_dump_rowcol (0, Numeric, Work, row, TRUE) ;
#endif
			ASSERT (Frpos [row] == i) ;
			/* row is not in the current front */
			DEBUG4 ((" NOT in front\n")) ;
			if (deg < rdeg [OUT]
			    /* break ties by picking the largest entry: */
			       || (deg == rdeg [OUT] && a > pivot [OUT])
			    /* break ties by picking the diagonal entry: */
			    /* || (deg == rdeg [OUT] && row == diag_row) */
			   )
			{
			    /* best row not in front, so far */
			    pivrow [OUT] = row ;
			    rdeg [OUT] = deg ;
			    pivot [OUT] = a ;
			}
		    }
		}

	    }
	    else
	    {

		/* this column is not in the front */
		for (i = 0 ; i < cdeg1 ; i++)
		{
		    double a ;
		    APPROX_ABS (a, Wxy [i]) ;
		    ASSERT (!SCALAR_IS_NAN (a)) ;
		    ASSERT (!SCALAR_IS_NAN (toler)) ;
		    if (SCALAR_IS_NONZERO (a) && a >= toler)
		    {
			row = Pattern [i] ;
			deg = Row_degree [row] ;
#ifndef NDEBUG
			DEBUG6 ((ID" candidate row "ID" deg "ID" absval %g\n",
			    i, row, deg, a)) ;
			UMF_dump_rowcol (0, Numeric, Work, row, TRUE) ;
#endif
			if (Frpos [row] >= 0 && Frpos [row] < fnrows)
			{
			    /* row is in the current front */
			    DEBUG4 ((" in front\n")) ;
			    if (deg < rdeg [IN]
			    /* break ties by picking the largest entry: */
			       || (deg == rdeg [IN] && a > pivot [IN])
			    /* break ties by picking the diagonal entry: */
			    /* || (deg == rdeg [IN] && row == diag_row) */
			       )
			    {
				/* best row in front, so far */
				pivrow [IN] = row ;
				rdeg [IN] = deg ;
				pivot [IN] = a ;
			    }
			}
			else
			{
			    /* row is not in the current front */
			    DEBUG4 ((" NOT in front\n")) ;
			    if (deg < rdeg [OUT]
			    /* break ties by picking the largest entry: */
			       || (deg == rdeg[OUT] && a > pivot [OUT])
			    /* break ties by picking the diagonal entry: */
			    /* || (deg == rdeg[OUT] && row == diag_row) */
			       )
			    {
				/* best row not in front, so far */
				pivrow [OUT] = row ;
				rdeg [OUT] = deg ;
				pivot [OUT] = a ;
			    }
			}
		    }
		}
	    }
	}
    }

    /* ---------------------------------------------------------------------- */
    /* NaN handling */
    /* ---------------------------------------------------------------------- */

    /* if cdeg1 > 0 then we must have found a pivot row ... unless NaN's */
    /* exist.  Try with no numerical tests if no pivot found. */

    if (cdeg1 > 0 && pivrow [IN] == EMPTY && pivrow [OUT] == EMPTY)
    {
	/* cleanup for the NaN case */
	DEBUG0 (("Found a NaN in pivot column!\n")) ;

	/* grab the first entry in the pivot column, ignoring degree, */
	/* numerical stability, and symmetric preference */
	row = Pattern [0] ;
	deg = Row_degree [row] ;
	if (Frpos [row] >= 0 && Frpos [row] < fnrows)
	{
	    /* row is in the current front */
	    DEBUG4 ((" in front\n")) ;
	    pivrow [IN] = row ;
	    rdeg [IN] = deg ;
	}
	else
	{
	    /* row is not in the current front */
	    DEBUG4 ((" NOT in front\n")) ;
	    pivrow [OUT] = row ;
	    rdeg [OUT] = deg ;
	}

	/* We are now guaranteed to have a pivot, no matter how broken */
	/* (non-IEEE compliant) the underlying numerical operators are. */
	/* This is particularly a problem for Microsoft compilers (they do */
	/* not handle NaN's properly). Now try to find a sparser pivot, if */
	/* possible. */

	for (i = 1 ; i < cdeg1 ; i++)
	{
	    row = Pattern [i] ;
	    deg = Row_degree [row] ;

	    if (Frpos [row] >= 0 && Frpos [row] < fnrows)
	    {
		/* row is in the current front */
		DEBUG4 ((" in front\n")) ;
		if (deg < rdeg [IN] || (deg == rdeg [IN] && row == diag_row))
		{
		    /* best row in front, so far */
		    pivrow [IN] = row ;
		    rdeg [IN] = deg ;
		}
	    }
	    else
	    {
		/* row is not in the current front */
		DEBUG4 ((" NOT in front\n")) ;
		if (deg < rdeg [OUT] || (deg == rdeg [OUT] && row == diag_row))
		{
		    /* best row not in front, so far */
		    pivrow [OUT] = row ;
		    rdeg [OUT] = deg ;
		}
	    }
	}
    }

    /* We found a pivot if there are entries (even zero ones) in pivot col */
    ASSERT (IMPLIES (cdeg1 > 0, pivrow[IN] != EMPTY || pivrow[OUT] != EMPTY)) ;

    /* If there are no entries in the pivot column, then no pivot is found */
    ASSERT (IMPLIES (cdeg1 == 0, pivrow[IN] == EMPTY && pivrow[OUT] == EMPTY)) ;

    /* ---------------------------------------------------------------------- */
    /* check for singular matrix */
    /* ---------------------------------------------------------------------- */

    if (cdeg1  == 0)
    {
	if (fnrows > 0)
	{
	    /*
		Get the pivrow [OUT][IN] from the current front.
		The frontal matrix looks like this:

			pivcol[OUT]
			|
			v
		x x x x 0   <- so grab this row as the pivrow [OUT][IN].
		x x x x 0
		x x x x 0
		0 0 0 0 0

		The current frontal matrix has some rows in it.  The degree
		of the pivcol[OUT] is zero.  The column is empty, and the
		current front does not contribute to it.

	    */
	    pivrow [IN] = Work->Frows [0] ;
	    DEBUGm4 (("Got zero pivrow[OUT][IN] "ID" from current front\n",
		pivrow [IN])) ;
	}
	else
	{

	    /*
		Get a pivot row from the row-merge tree, use as
		pivrow [OUT][OUT].   pivrow [IN] remains EMPTY.
		This can only happen if the current front is 0-by-0.
	    */

	    Int *Front_leftmostdesc, *Front_1strow, *Front_new1strow, row1,
		row2, fleftmost, nfr, n_row, frontid ;

	    ASSERT (Work->fncols == 0) ;

	    Front_leftmostdesc = Symbolic->Front_leftmostdesc ;
	    Front_1strow = Symbolic->Front_1strow ;
	    Front_new1strow = Work->Front_new1strow ;
	    nfr = Symbolic->nfr ;
	    n_row = Numeric->n_row ;
	    frontid = Work->frontid ;

	    DEBUGm4 (("Note: pivcol: "ID" is empty front "ID"\n",
		pivcol, frontid)) ;
#ifndef NDEBUG
	    DEBUG1 (("Calling dump rowmerge\n")) ;
	    UMF_dump_rowmerge (Numeric, Symbolic, Work) ;
#endif

	    /* Row-merge set is the non-pivotal rows in the range */
	    /* Front_new1strow [Front_leftmostdesc [frontid]] to */
	    /* Front_1strow [frontid+1] - 1. */
	    /* If this is empty, then use the empty rows, in the range */
	    /* Front_new1strow [nfr] to n_row-1. */
	    /* If this too is empty, then pivrow [OUT] will be empty. */
	    /* In both cases, update Front_new1strow [...]. */

	    fleftmost = Front_leftmostdesc [frontid] ;
	    row1 = Front_new1strow [fleftmost] ;
	    row2 = Front_1strow [frontid+1] - 1 ;
	    DEBUG1 (("Leftmost: "ID" Rows ["ID" to "ID"] srch ["ID" to "ID"]\n",
		fleftmost, Front_1strow [frontid], row2, row1, row2)) ;

	    /* look in the range row1 ... row2 */
	    for (row = row1 ; row <= row2 ; row++)
	    {
		DEBUG3 (("   Row: "ID"\n", row)) ;
		if (NON_PIVOTAL_ROW (row))
		{
		    /* found it */
		    DEBUG3 (("   Row: "ID" found\n", row)) ;
		    ASSERT (Frpos [row] == EMPTY) ;
		    pivrow [OUT] = row ;
		    DEBUGm4 (("got row merge pivrow %d\n", pivrow [OUT])) ;
		    break ;
		}
	    }
	    Front_new1strow [fleftmost] = row ;

	    if (pivrow [OUT] == EMPTY)
	    {
		/* not found, look in empty row set in "dummy" front */
		row1 = Front_new1strow [nfr] ;
		row2 = n_row-1 ;
		DEBUG3 (("Empty: "ID" Rows ["ID" to "ID"] srch["ID" to "ID"]\n",
		    nfr, Front_1strow [nfr], row2, row1, row2)) ;

		/* look in the range row1 ... row2 */
		for (row = row1 ; row <= row2 ; row++)
		{
		    DEBUG3 (("   Empty Row: "ID"\n", row)) ;
		    if (NON_PIVOTAL_ROW (row))
		    {
			/* found it */
			DEBUG3 (("   Empty Row: "ID" found\n", row)) ;
			ASSERT (Frpos [row] == EMPTY) ;
			pivrow [OUT] = row ;
			DEBUGm4 (("got dummy row pivrow %d\n", pivrow [OUT])) ;
			break ;
		    }
		}
		Front_new1strow [nfr] = row ;
	    }

	    if (pivrow [OUT] == EMPTY)
	    {
		/* Row-merge set is empty.  We can just discard */
		/* the candidate pivot column. */
		DEBUG0 (("Note: row-merge set empty\n")) ;
		DEBUGm4 (("got no pivrow \n")) ;
		return (UMFPACK_WARNING_singular_matrix) ;
	    }
	}
    }

    /* ---------------------------------------------------------------------- */
    /* construct the candidate row in the front, if any */
    /* ---------------------------------------------------------------------- */

#ifndef NDEBUG
    /* check Wrp */
    ASSERT (Work->Wrpflag > 0) ;
    if (UMF_debug > 0 || Work->n_col < 1000)
    {
	for (i = 0 ; i < Work->n_col ; i++)
	{
	    ASSERT (Wrp [i] < Work->Wrpflag) ;
	}
    }
#endif

#ifndef NDEBUG
    DEBUG4 (("pivrow [IN]: "ID"\n", pivrow [IN])) ;
    UMF_dump_rowcol (0, Numeric, Work, pivrow [IN], TRUE) ;
#endif

    if (pivrow [IN] != EMPTY)
    {

	/* the row merge candidate row is not pivrow [IN] */
	freebie [IN] = (pivrow [IN] == prior_pivrow [IN]) && (cdeg1  > 0) ;
	ASSERT (cdeg1  >= 0) ;

	if (!freebie [IN])
	{
	    /* include current front in the degree of this row */

	    Fcpos = Work->Fcpos ;
	    fncols = Work->fncols ;

	    Wrpflag = Work->Wrpflag ;

	    /* -------------------------------------------------------------- */
	    /* construct the pattern of the IN row */
	    /* -------------------------------------------------------------- */

#ifndef NDEBUG
	    /* check Fcols */
	    DEBUG5 (("ROW ASSEMBLE: rdeg "ID"\nREDUCE ROW "ID"\n",
		fncols, pivrow [IN])) ;
	    for (j = 0 ; j < fncols ; j++)
	    {
		col = Work->Fcols [j] ;
		ASSERT (col >= 0 && col < Work->n_col) ;
		ASSERT (Fcpos [col] >= 0) ;
	    }
	    if (UMF_debug > 0 || Work->n_col < 1000)
	    {
		Int cnt = fncols ;
		for (col = 0 ; col < Work->n_col ; col++)
		{
		    if (Fcpos [col] < 0) cnt++ ;
		}
		ASSERT (cnt == Work->n_col) ;
	    }
#endif

	    rdeg [IN] = fncols ;

	    ASSERT (pivrow [IN] >= 0 && pivrow [IN] < Work->n_row) ;
	    ASSERT (NON_PIVOTAL_ROW (pivrow [IN])) ;

	    /* add the pivot column itself */
	    ASSERT (Wrp [pivcol] != Wrpflag) ;
	    if (Fcpos [pivcol] < 0)
	    {
		DEBUG3 (("Adding pivot col to pivrow [IN] pattern\n")) ;
		if (rdeg [IN] >= max_rdeg)
		{
		    /* :: pattern change (in) :: */
		    return (UMFPACK_ERROR_different_pattern) ;
		}
		Wrp [pivcol] = Wrpflag ;
		W_i [rdeg [IN]++] = pivcol ;
	    }

	    tpi = Row_tuples [pivrow [IN]] ;
	    if (tpi)
	    {
		tp = (Tuple *) (Memory + tpi) ;
		tp1 = tp ;
		tp2 = tp ;
		tpend = tp + Row_tlen [pivrow [IN]] ;
		for ( ; tp < tpend ; tp++)
		{
		    e = tp->e ;
		    ASSERT (e > 0 && e <= Work->nel) ;
		    if (!E [e])
		    {
			continue ;	/* element already deallocated */
		    }
		    f = tp->f ;
		    p = Memory + E [e] ;
		    ep = (Element *) p ;
		    p += UNITS (Element, 1) ;
		    Cols = (Int *) p ;
		    ncols = ep->ncols ;
		    Rows = Cols + ncols ;
		    if (Rows [f] == EMPTY)
		    {
			continue ;	/* row already assembled */
		    }
		    ASSERT (pivrow [IN] == Rows [f]) ;

		    for (j = 0 ; j < ncols ; j++)
		    {
			col = Cols [j] ;
			ASSERT (col >= EMPTY && col < Work->n_col) ;
			if ((col >= 0) && (Wrp [col] != Wrpflag)
			    && Fcpos [col] <0)
			{
			    ASSERT (NON_PIVOTAL_COL (col)) ;
			    if (rdeg [IN] >= max_rdeg)
			    {
				/* :: pattern change (rdeg in failure) :: */
				DEBUGm4 (("rdeg [IN] >= max_rdeg failure\n")) ;
				return (UMFPACK_ERROR_different_pattern) ;
			    }
			    Wrp [col] = Wrpflag ;
			    W_i [rdeg [IN]++] = col ;
			}
		    }

		    *tp2++ = *tp ;	/* leave the tuple in the list */
		}
		Row_tlen [pivrow [IN]] = tp2 - tp1 ;
	    }

#ifndef NDEBUG
	    DEBUG4 (("Reduced IN row:\n")) ;
	    for (j = 0 ; j < fncols ; j++)
	    {
		DEBUG6 ((" "ID" "ID" "ID"\n",
		    j, Work->Fcols [j], Fcpos [Work->Fcols [j]])) ;
		ASSERT (Fcpos [Work->Fcols [j]] >= 0) ;
	    }
	    for (j = fncols ; j < rdeg [IN] ; j++)
	    {
		DEBUG6 ((" "ID" "ID" "ID"\n", j, W_i [j], Wrp [W_i [j]]));
		ASSERT (W_i [j] >= 0 && W_i [j] < Work->n_col) ;
		ASSERT (Wrp [W_i [j]] == Wrpflag) ;
	    }
	    /* mark the end of the pattern in case we scan it by mistake */
	    /* Note that this means W_i must be of size >= fncols_max + 1 */
	    W_i [rdeg [IN]] = EMPTY ;
#endif

	    /* rdeg [IN] is now the exact degree of the IN row */

	    /* clear Work->Wrp. */
	    Work->Wrpflag++ ;
	    /* All Wrp [0..n_col] is now < Wrpflag */
	}
    }

#ifndef NDEBUG
    /* check Wrp */
    if (UMF_debug > 0 || Work->n_col < 1000)
    {
	for (i = 0 ; i < Work->n_col ; i++)
	{
	    ASSERT (Wrp [i] < Work->Wrpflag) ;
	}
    }
#endif

    /* ---------------------------------------------------------------------- */
    /* construct the candidate row not in the front, if any */
    /* ---------------------------------------------------------------------- */

#ifndef NDEBUG
    DEBUG4 (("pivrow [OUT]: "ID"\n", pivrow [OUT])) ;
    UMF_dump_rowcol (0, Numeric, Work, pivrow [OUT], TRUE) ;
#endif

    /* If this is a candidate row from the row merge set, force it to be */
    /* scanned (ignore prior_pivrow [OUT]). */

    if (pivrow [OUT] != EMPTY)
    {
	freebie [OUT] = (pivrow [OUT] == prior_pivrow [OUT]) && cdeg1  > 0 ;
	ASSERT (cdeg1  >= 0) ;

	if (!freebie [OUT])
	{

	    Wrpflag = Work->Wrpflag ;

	    /* -------------------------------------------------------------- */
	    /* construct the pattern of the row */
	    /* -------------------------------------------------------------- */

	    rdeg [OUT] = 0 ;

	    ASSERT (pivrow [OUT] >= 0 && pivrow [OUT] < Work->n_row) ;
	    ASSERT (NON_PIVOTAL_ROW (pivrow [OUT])) ;

	    /* add the pivot column itself */
	    ASSERT (Wrp [pivcol] != Wrpflag) ;
	    DEBUG3 (("Adding pivot col to pivrow [OUT] pattern\n")) ;
	    if (rdeg [OUT] >= max_rdeg)
	    {
		/* :: pattern change (out) :: */
		return (UMFPACK_ERROR_different_pattern) ;
	    }
	    Wrp [pivcol] = Wrpflag ;
	    W_o [rdeg [OUT]++] = pivcol ;

	    tpi = Row_tuples [pivrow [OUT]] ;
	    if (tpi)
	    {
		tp = (Tuple *) (Memory + tpi) ;
		tp1 = tp ;
		tp2 = tp ;
		tpend = tp + Row_tlen [pivrow [OUT]] ;
		for ( ; tp < tpend ; tp++)
		{
		    e = tp->e ;
		    ASSERT (e > 0 && e <= Work->nel) ;
		    if (!E [e])
		    {
			continue ;	/* element already deallocated */
		    }
		    f = tp->f ;
		    p = Memory + E [e] ;
		    ep = (Element *) p ;
		    p += UNITS (Element, 1) ;
		    Cols = (Int *) p ;
		    ncols = ep->ncols ;
		    Rows = Cols + ncols ;
		    if (Rows [f] == EMPTY)
		    {
			continue ;	/* row already assembled */
		    }
		    ASSERT (pivrow [OUT] == Rows [f]) ;

		    for (j = 0 ; j < ncols ; j++)
		    {
			col = Cols [j] ;
			ASSERT (col >= EMPTY && col < Work->n_col) ;
			if ((col >= 0) && (Wrp [col] != Wrpflag))
			{
			    ASSERT (NON_PIVOTAL_COL (col)) ;
			    if (rdeg [OUT] >= max_rdeg)
			    {
				/* :: pattern change (rdeg out failure) :: */
				DEBUGm4 (("rdeg [OUT] failure\n")) ;
				return (UMFPACK_ERROR_different_pattern) ;
			    }
			    Wrp [col] = Wrpflag ;
			    W_o [rdeg [OUT]++] = col ;
			}
		    }
		    *tp2++ = *tp ;	/* leave the tuple in the list */
		}
		Row_tlen [pivrow [OUT]] = tp2 - tp1 ;
	    }

#ifndef NDEBUG
	    DEBUG4 (("Reduced row OUT:\n")) ;
	    for (j = 0 ; j < rdeg [OUT] ; j++)
	    {
		DEBUG6 ((" "ID" "ID" "ID"\n", j, W_o [j], Wrp [W_o [j]])) ;
		ASSERT (W_o [j] >= 0 && W_o [j] < Work->n_col) ;
		ASSERT (Wrp [W_o [j]] == Wrpflag) ;
	    }
	    /* mark the end of the pattern in case we scan it by mistake */
	    /* Note that this means W_o must be of size >= fncols_max + 1 */
	    W_o [rdeg [OUT]] = EMPTY ;
#endif

	    /* rdeg [OUT] is now the exact degree of the row */

	    /* clear Work->Wrp. */
	    Work->Wrpflag++ ;
	    /* All Wrp [0..n] is now < Wrpflag */

	}

    }
    DEBUG5 (("Row_search end ] \n")) ;

#ifndef NDEBUG
    /* check Wrp */
    if (UMF_debug > 0 || Work->n_col < 1000)
    {
	for (i = 0 ; i < Work->n_col ; i++)
	{
	    ASSERT (Wrp [i] < Work->Wrpflag) ;
	}
    }
#endif

    return (UMFPACK_OK) ;
}
示例#6
0
GLOBAL Int UMF_start_front    /* returns TRUE if successful, FALSE otherwise */
(
    Int chain,
    NumericType *Numeric,
    WorkType *Work,
    SymbolicType *Symbolic
)
{
    Int fnrows_max, fncols_max, fnr2, fnc2, fsize, fcurr_size, maxfrsize,
	overflow, nb, f, cdeg ;
    double maxbytes ;

    nb = Symbolic->nb ;
    fnrows_max = Symbolic->Chain_maxrows [chain] ;
    fncols_max = Symbolic->Chain_maxcols [chain] ;

    DEBUGm2 (("Start Front for chain "ID".  fnrows_max "ID" fncols_max "ID"\n",
	chain, fnrows_max, fncols_max)) ;

    Work->fnrows_max = fnrows_max ;
    Work->fncols_max = fncols_max ;
    Work->any_skip = FALSE ;

    maxbytes = sizeof (Entry) *
	(double) (fnrows_max + nb) * (double) (fncols_max + nb) ;
    fcurr_size = Work->fcurr_size ;

    if (Symbolic->prefer_diagonal)
    {
	/* Get a rough upper bound on the degree of the first pivot column in
	 * this front.  Note that Col_degree is not maintained if diagonal
	 * pivoting is preferred.  For most matrices, the first pivot column
	 * of the first frontal matrix of a new chain has only one tuple in
	 * it anyway, so this bound is exact in that case. */
	Int col, tpi, e, *E, *Col_tuples, *Col_tlen, *Cols ;
	Tuple *tp, *tpend ;
	Unit *Memory, *p ;
	Element *ep ;
	E = Work->E ;
	Memory = Numeric->Memory ;
	Col_tuples = Numeric->Lip ;
	Col_tlen = Numeric->Lilen ;
	col = Work->nextcand ;
	tpi = Col_tuples [col] ;
	tp = (Tuple *) Memory + tpi ;
	tpend = tp + Col_tlen [col] ;
	cdeg = 0 ;
	DEBUGm3 (("\n=============== start front: col "ID" tlen "ID"\n",
		col, Col_tlen [col])) ;
	for ( ; tp < tpend ; tp++)
	{
	    DEBUG1 (("Tuple ("ID","ID")\n", tp->e, tp->f)) ;
	    e = tp->e ;
	    if (!E [e]) continue ;
	    f = tp->f ;
	    p = Memory + E [e] ;
	    ep = (Element *) p ;
	    p += UNITS (Element, 1) ;
	    Cols = (Int *) p ;
	    if (Cols [f] == EMPTY) continue ;
	    DEBUG1 (("  nrowsleft "ID"\n", ep->nrowsleft)) ;
	    cdeg += ep->nrowsleft ;
	}
#ifndef NDEBUG
	DEBUGm3 (("start front cdeg: "ID" col "ID"\n", cdeg, col)) ;
	UMF_dump_rowcol (1, Numeric, Work, col, FALSE) ;
#endif

	/* cdeg is now the rough upper bound on the degree of the next pivot
	 * column. */

	/* If AMD was called, we know the maximum number of nonzeros in any
	 * column of L.  Use this as an upper bound for cdeg, but add 2 to
	 * account for a small amount of off-diagonal pivoting. */
	if (Symbolic->amd_dmax > 0)
	{
	    cdeg = MIN (cdeg, Symbolic->amd_dmax) ;
	}

	/* Increase it to account for larger columns later on.
	 * Also ensure that it's larger than zero. */
	cdeg += 2 ;

	/* cdeg cannot be larger than fnrows_max */
	cdeg = MIN (cdeg, fnrows_max) ;

    }
    else
    {
	/* don't do the above cdeg computation */
	cdeg = 0 ;
    }

    DEBUGm2 (("fnrows max "ID" fncols_max "ID"\n", fnrows_max, fncols_max)) ;

    /* the current frontal matrix is empty */
    ASSERT (Work->fnrows == 0 && Work->fncols == 0 && Work->fnpiv == 0) ;

    /* maximum row dimension is always odd, to avoid bad cache effects */
    ASSERT (fnrows_max >= 0) ;
    ASSERT (fnrows_max % 2 == 1) ;

    /* ----------------------------------------------------------------------
     * allocate working array for current frontal matrix:
     * minimum size: 1-by-1
     * maximum size: fnrows_max-by-fncols_max
     * desired size:
     *
     *   if Numeric->front_alloc_init >= 0:
     *
     *	    for unsymmetric matrices:
     *	    Numeric->front_alloc_init * (fnrows_max-by-fncols_max)
     *
     *	    for symmetric matrices (diagonal pivoting preference, actually):
     *	    Numeric->front_alloc_init * (fnrows_max-by-fncols_max), or
     *	    cdeg*cdeg, whichever is smaller.
     *
     *   if Numeric->front_alloc_init < 0:
     *	    allocate a front of size -Numeric->front_alloc_init.
     *
     * Allocate the whole thing if it's small (less than 2*nb^2).  Make sure the
     * leading dimension of the frontal matrix is odd.
     *
     * Also allocate the nb-by-nb LU block, the dr-by-nb L block, and the
     * nb-by-dc U block.
     * ---------------------------------------------------------------------- */

    /* get the maximum front size, avoiding integer overflow */
    overflow = INT_OVERFLOW (maxbytes) ;
    if (overflow)
    {
	/* :: int overflow, max front size :: */
	maxfrsize = Int_MAX / sizeof (Entry) ;
    }
    else
    {
	maxfrsize = (fnrows_max + nb) * (fncols_max + nb) ;
    }
    ASSERT (!INT_OVERFLOW ((double) maxfrsize * sizeof (Entry))) ;

    if (Numeric->front_alloc_init < 0)
    {
	/* allocate a front of -Numeric->front_alloc_init entries */
	fsize = -Numeric->front_alloc_init ;
	fsize = MAX (1, fsize) ;
    }
    else
    {
	if (INT_OVERFLOW (Numeric->front_alloc_init * maxbytes))
	{
	    /* :: int overflow, requested front size :: */
	    fsize = Int_MAX / sizeof (Entry) ;
	}
	else
	{
	    fsize = Numeric->front_alloc_init * maxfrsize ;
	}

	if (cdeg > 0)
	{
	    /* diagonal pivoting is in use.  cdeg was computed above */
	    Int fsize2 ;

	    /* add the L and U blocks */
	    cdeg += nb ;

	    if (INT_OVERFLOW (((double) cdeg * (double) cdeg) * sizeof (Entry)))
	    {
		/* :: int overflow, symmetric front size :: */
		fsize2 = Int_MAX / sizeof (Entry) ;
	    }
	    else
	    {
		fsize2 = MAX (cdeg * cdeg, fcurr_size) ;
	    }
	    fsize = MIN (fsize, fsize2) ;
	}
    }

    fsize = MAX (fsize, 2*nb*nb) ;

    /* fsize and maxfrsize are now safe from integer overflow.  They both
     * include the size of the pivot blocks. */
    ASSERT (!INT_OVERFLOW ((double) fsize * sizeof (Entry))) ;

    Work->fnrows_new = 0 ;
    Work->fncols_new = 0 ;

    /* desired size is fnr2-by-fnc2 (includes L and U blocks): */
    DEBUGm2 (("    fsize "ID"  fcurr_size "ID"\n", fsize, fcurr_size)) ;
    DEBUGm2 (("    maxfrsize "ID"  fnr_curr "ID" fnc_curr "ID"\n", maxfrsize,
	Work->fnr_curr, Work->fnc_curr)) ;

    if (fsize >= maxfrsize && !overflow)
    {
	/* max working array is small, allocate all of it */
	fnr2 = fnrows_max + nb ;
	fnc2 = fncols_max + nb ;
	fsize = maxfrsize ;
	DEBUGm1 (("   sufficient for ("ID"+"ID")-by-("ID"+"ID")\n",
	    fnrows_max, nb, fncols_max, nb)) ;
    }
    else
    {
	/* allocate a smaller working array */
	if (fnrows_max <= fncols_max)
	{
	    fnr2 = (Int) sqrt ((double) fsize) ;
	    /* make sure fnr2 is odd */
	    fnr2 = MAX (fnr2, 1) ;
	    if (fnr2 % 2 == 0) fnr2++ ;
	    fnr2 = MIN (fnr2, fnrows_max + nb) ;
	    fnc2 = fsize / fnr2 ;
	}
	else
	{
	    fnc2 = (Int) sqrt ((double) fsize) ;
	    fnc2 = MIN (fnc2, fncols_max + nb) ;
	    fnr2 = fsize / fnc2 ;
	    /* make sure fnr2 is odd */
	    fnr2 = MAX (fnr2, 1) ;
	    if (fnr2 % 2 == 0)
	    {
		fnr2++ ;
		fnc2 = fsize / fnr2 ;
	    }
	}
	DEBUGm1 (("   smaller "ID"-by-"ID"\n", fnr2, fnc2)) ;
    }
    fnr2 = MIN (fnr2, fnrows_max + nb) ;
    fnc2 = MIN (fnc2, fncols_max + nb) ;
    ASSERT (fnr2 % 2 == 1) ;
    ASSERT (fnr2 * fnc2 <= fsize) ;

    fnr2 -= nb ;
    fnc2 -= nb ;
    ASSERT (fnr2 >= 0) ;
    ASSERT (fnc2 >= 0) ;

    if (fsize > fcurr_size)
    {
	DEBUGm1 (("   Grow front \n")) ;
	Work->do_grow = TRUE ;
	if (!UMF_grow_front (Numeric, fnr2, fnc2, Work, -1))
	{
	    /* since the minimum front size is 1-by-1, it would be nearly
	     * impossible to run out of memory here. */
	    DEBUGm4 (("out of memory: start front\n")) ;
	    return (FALSE) ;
	}
    }
    else
    {
	/* use the existing front */
	DEBUGm1 (("   existing front ok\n")) ;
	Work->fnr_curr = fnr2 ;
	Work->fnc_curr = fnc2 ;
	Work->Flblock  = Work->Flublock + nb * nb ;
	Work->Fublock  = Work->Flblock  + nb * fnr2 ;
	Work->Fcblock  = Work->Fublock  + nb * fnc2 ;
    }
    ASSERT (Work->Flblock  == Work->Flublock + Work->nb*Work->nb) ;
    ASSERT (Work->Fublock  == Work->Flblock  + Work->fnr_curr*Work->nb) ;
    ASSERT (Work->Fcblock  == Work->Fublock  + Work->nb*Work->fnc_curr) ;
    return (TRUE) ;
}
示例#7
0
GLOBAL Int UMF_create_element
(
    NumericType *Numeric,
    WorkType *Work,
    SymbolicType *Symbolic
)
{
    /* ---------------------------------------------------------------------- */
    /* local variables */
    /* ---------------------------------------------------------------------- */

    Int j, col, row, *Fcols, *Frows, fnrows, fncols, *Cols, len, needunits, t1,
        t2, size, e, i, *E, *Fcpos, *Frpos, *Rows, eloc, fnr_curr, f,
        got_memory, *Row_tuples, *Row_degree, *Row_tlen, *Col_tuples, max_mark,
        *Col_degree, *Col_tlen, nn, n_row, n_col, r2, c2, do_Fcpos ;
    Entry *C, *Fcol ;
    Element *ep ;
    Unit *p, *Memory ;
    Tuple *tp, *tp1, *tp2, tuple, *tpend ;
#ifndef NDEBUG
    DEBUG2 (("FRONTAL WRAPUP\n")) ;
    UMF_dump_current_front (Numeric, Work, TRUE) ;
#endif

    /* ---------------------------------------------------------------------- */
    /* get parameters */
    /* ---------------------------------------------------------------------- */

    ASSERT (Work->fnpiv == 0) ;
    ASSERT (Work->fnzeros == 0) ;
    Row_degree = Numeric->Rperm ;
    Row_tuples = Numeric->Uip ;
    Row_tlen   = Numeric->Uilen ;
    Col_degree = Numeric->Cperm ;
    Col_tuples = Numeric->Lip ;
    Col_tlen   = Numeric->Lilen ;
    n_row = Work->n_row ;
    n_col = Work->n_col ;
    nn = MAX (n_row, n_col) ;
    Fcols = Work->Fcols ;
    Frows = Work->Frows ;
    Fcpos = Work->Fcpos ;
    Frpos = Work->Frpos ;
    Memory = Numeric->Memory ;
    fncols = Work->fncols ;
    fnrows = Work->fnrows ;

    tp = (Tuple *) NULL ;
    tp1 = (Tuple *) NULL ;
    tp2 = (Tuple *) NULL ;

    /* ---------------------------------------------------------------------- */
    /* add the current frontal matrix to the degrees of each column */
    /* ---------------------------------------------------------------------- */

    if (!Symbolic->fixQ)
    {
        /* but only if the column ordering is not fixed */
#pragma ivdep
        for (j = 0 ; j < fncols ; j++)
        {
            /* add the current frontal matrix to the degree */
            ASSERT (Fcols [j] >= 0 && Fcols [j] < n_col) ;
            Col_degree [Fcols [j]] += fnrows ;
        }
    }

    /* ---------------------------------------------------------------------- */
    /* add the current frontal matrix to the degrees of each row */
    /* ---------------------------------------------------------------------- */

#pragma ivdep
    for (i = 0 ; i < fnrows ; i++)
    {
        /* add the current frontal matrix to the degree */
        ASSERT (Frows [i] >= 0 && Frows [i] < n_row) ;
        Row_degree [Frows [i]] += fncols ;
    }

    /* ---------------------------------------------------------------------- */
    /* Reset the external degree counters */
    /* ---------------------------------------------------------------------- */

    E = Work->E ;
    max_mark = MAX_MARK (nn) ;

    if (!Work->pivcol_in_front)
    {
        /* clear the external column degrees. no more Usons of current front */
        Work->cdeg0 += (nn + 1) ;
        if (Work->cdeg0 >= max_mark)
        {
            /* guard against integer overflow.  This is very rare */
            DEBUG1 (("Integer overflow, cdeg\n")) ;
            Work->cdeg0 = 1 ;
#pragma ivdep
            for (e = 1 ; e <= Work->nel ; e++)
            {
                if (E [e])
                {
                    ep = (Element *) (Memory + E [e]) ;
                    ep->cdeg = 0 ;
                }
            }
        }
    }

    if (!Work->pivrow_in_front)
    {
        /* clear the external row degrees.  no more Lsons of current front */
        Work->rdeg0 += (nn + 1) ;
        if (Work->rdeg0 >= max_mark)
        {
            /* guard against integer overflow.  This is very rare */
            DEBUG1 (("Integer overflow, rdeg\n")) ;
            Work->rdeg0 = 1 ;
#pragma ivdep
            for (e = 1 ; e <= Work->nel ; e++)
            {
                if (E [e])
                {
                    ep = (Element *) (Memory + E [e]) ;
                    ep->rdeg = 0 ;
                }
            }
        }
    }

    /* ---------------------------------------------------------------------- */
    /* clear row/col offsets */
    /* ---------------------------------------------------------------------- */

    if (!Work->pivrow_in_front)
    {
#pragma ivdep
        for (j = 0 ; j < fncols ; j++)
        {
            Fcpos [Fcols [j]] = EMPTY ;
        }
    }

    if (!Work->pivcol_in_front)
    {
#pragma ivdep
        for (i = 0 ; i < fnrows ; i++)
        {
            Frpos [Frows [i]] = EMPTY ;
        }
    }

    if (fncols <= 0 || fnrows <= 0)
    {
        /* no element to create */
        DEBUG2 (("Element evaporation\n")) ;
        Work->prior_element = EMPTY ;
        return (TRUE) ;
    }

    /* ---------------------------------------------------------------------- */
    /* create element for later assembly */
    /* ---------------------------------------------------------------------- */

#ifndef NDEBUG
    UMF_allocfail = FALSE ;
    if (UMF_gprob > 0)
    {
        double rrr = ((double) (rand ( ))) / (((double) RAND_MAX) + 1) ;
        DEBUG4 (("Check random %e %e\n", rrr, UMF_gprob)) ;
        UMF_allocfail = rrr < UMF_gprob ;
        if (UMF_allocfail) DEBUGm2 (("Random garbage collection (create)\n"));
    }
#endif

    needunits = 0 ;
    got_memory = FALSE ;
    eloc = UMF_mem_alloc_element (Numeric, fnrows, fncols, &Rows, &Cols, &C,
                                  &needunits, &ep) ;

    /* if UMF_get_memory needs to be called */
    if (Work->do_grow)
    {
        /* full compaction of current frontal matrix, since UMF_grow_front will
         * be called next anyway. */
        r2 = fnrows ;
        c2 = fncols ;
        do_Fcpos = FALSE ;
    }
    else
    {
        /* partial compaction. */
        r2 = MAX (fnrows, Work->fnrows_new + 1) ;
        c2 = MAX (fncols, Work->fncols_new + 1) ;
        /* recompute Fcpos if pivot row is in the front */
        do_Fcpos = Work->pivrow_in_front ;
    }

    if (!eloc)
    {
        /* Do garbage collection, realloc, and try again. */
        /* Compact the current front if it needs to grow anyway. */
        /* Note that there are no pivot rows or columns in the current front */
        DEBUGm3 (("get_memory from umf_create_element, 1\n")) ;
        if (!UMF_get_memory (Numeric, Work, needunits, r2, c2, do_Fcpos))
        {
            /* :: out of memory in umf_create_element (1) :: */
            DEBUGm4 (("out of memory: create element (1)\n")) ;
            return (FALSE) ;	/* out of memory */
        }
        got_memory = TRUE ;
        Memory = Numeric->Memory ;
        eloc = UMF_mem_alloc_element (Numeric, fnrows, fncols, &Rows, &Cols, &C,
                                      &needunits, &ep) ;
        ASSERT (eloc >= 0) ;
        if (!eloc)
        {
            /* :: out of memory in umf_create_element (2) :: */
            DEBUGm4 (("out of memory: create element (2)\n")) ;
            return (FALSE) ;	/* out of memory */
        }
    }

    e = ++(Work->nel) ;	/* get the name of this new frontal matrix */
    Work->prior_element = e ;
    DEBUG8 (("wrapup e "ID" nel "ID"\n", e, Work->nel)) ;

    ASSERT (e > 0 && e < Work->elen) ;
    ASSERT (E [e] == 0) ;
    E [e] = eloc ;

    if (Work->pivcol_in_front)
    {
        /* the new element is a Uson of the next frontal matrix */
        ep->cdeg = Work->cdeg0 ;
    }

    if (Work->pivrow_in_front)
    {
        /* the new element is an Lson of the next frontal matrix */
        ep->rdeg = Work->rdeg0 ;
    }

    /* ---------------------------------------------------------------------- */
    /* copy frontal matrix into the new element */
    /* ---------------------------------------------------------------------- */

#pragma ivdep
    for (i = 0 ; i < fnrows ; i++)
    {
        Rows [i] = Frows [i] ;
    }
#pragma ivdep
    for (i = 0 ; i < fncols ; i++)
    {
        Cols [i] = Fcols [i] ;
    }
    Fcol = Work->Fcblock ;
    DEBUG0 (("copy front "ID" by "ID"\n", fnrows, fncols)) ;
    fnr_curr = Work->fnr_curr ;
    ASSERT (fnr_curr >= 0 && fnr_curr % 2 == 1) ;
    for (j = 0 ; j < fncols ; j++)
    {
        copy_column (fnrows, Fcol, C) ;
        Fcol += fnr_curr ;
        C += fnrows ;
    }

    DEBUG8 (("element copied\n")) ;

    /* ---------------------------------------------------------------------- */
    /* add tuples for the new element */
    /* ---------------------------------------------------------------------- */

    tuple.e = e ;

    if (got_memory)
    {

        /* ------------------------------------------------------------------ */
        /* UMF_get_memory ensures enough space exists for each new tuple */
        /* ------------------------------------------------------------------ */

        /* place (e,f) in the element list of each column */
        for (tuple.f = 0 ; tuple.f < fncols ; tuple.f++)
        {
            col = Fcols [tuple.f] ;
            ASSERT (col >= 0 && col < n_col) ;
            ASSERT (NON_PIVOTAL_COL (col)) ;
            ASSERT (Col_tuples [col]) ;
            tp = ((Tuple *) (Memory + Col_tuples [col])) + Col_tlen [col]++ ;
            *tp = tuple ;
        }

        /* ------------------------------------------------------------------ */

        /* place (e,f) in the element list of each row */
        for (tuple.f = 0 ; tuple.f < fnrows ; tuple.f++)
        {
            row = Frows [tuple.f] ;
            ASSERT (row >= 0 && row < n_row) ;
            ASSERT (NON_PIVOTAL_ROW (row)) ;
            ASSERT (Row_tuples [row]) ;
            tp = ((Tuple *) (Memory + Row_tuples [row])) + Row_tlen [row]++ ;
            *tp = tuple ;
        }

    }
    else
    {

        /* ------------------------------------------------------------------ */
        /* place (e,f) in the element list of each column */
        /* ------------------------------------------------------------------ */

        /* might not have enough space for each tuple */

        for (tuple.f = 0 ; tuple.f < fncols ; tuple.f++)
        {
            col = Fcols [tuple.f] ;
            ASSERT (col >= 0 && col < n_col) ;
            ASSERT (NON_PIVOTAL_COL (col)) ;
            t1 = Col_tuples [col] ;
            DEBUG1 (("Placing on col:"ID" , tuples at "ID"\n",
                     col, Col_tuples [col])) ;

            size = 0 ;
            len = 0 ;

            if (t1)
            {
                p = Memory + t1 ;
                tp = (Tuple *) p ;
                size = GET_BLOCK_SIZE (p) ;
                len = Col_tlen [col] ;
                tp2 = tp + len ;
            }

            needunits = UNITS (Tuple, len + 1) ;
            DEBUG1 (("len: "ID" size: "ID" needunits: "ID"\n",
                     len, size, needunits));

            if (needunits > size && t1)
            {
                /* prune the tuples */
                tp1 = tp ;
                tp2 = tp ;
                tpend = tp + len ;
                for ( ; tp < tpend ; tp++)
                {
                    e = tp->e ;
                    ASSERT (e > 0 && e <= Work->nel) ;
                    if (!E [e]) continue ;   /* element already deallocated */
                    f = tp->f ;
                    p = Memory + E [e] ;
                    ep = (Element *) p ;
                    p += UNITS (Element, 1) ;
                    Cols = (Int *) p ;
                    ;
                    if (Cols [f] == EMPTY) continue ;	/* already assembled */
                    ASSERT (col == Cols [f]) ;
                    *tp2++ = *tp ;	/* leave the tuple in the list */
                }
                len = tp2 - tp1 ;
                Col_tlen [col] = len ;
                needunits = UNITS (Tuple, len + 1) ;
            }

            if (needunits > size)
            {
                /* no room exists - reallocate elsewhere */
                DEBUG1 (("REALLOCATE Col: "ID", size "ID" to "ID"\n",
                         col, size, 2*needunits)) ;

#ifndef NDEBUG
                UMF_allocfail = FALSE ;
                if (UMF_gprob > 0)  /* a double relop, but ignore NaN case */
                {
                    double rrr = ((double) (rand ( ))) /
                                 (((double) RAND_MAX) + 1) ;
                    DEBUG1 (("Check random %e %e\n", rrr, UMF_gprob)) ;
                    UMF_allocfail = rrr < UMF_gprob ;
                    if (UMF_allocfail) DEBUGm2 (("Random gar. (col tuple)\n")) ;
                }
#endif

                needunits = MIN (2*needunits, (Int) UNITS (Tuple, nn)) ;
                t2 = UMF_mem_alloc_tail_block (Numeric, needunits) ;
                if (!t2)
                {
                    /* :: get memory in umf_create_element (1) :: */
                    /* get memory, reconstruct all tuple lists, and return */
                    /* Compact the current front if it needs to grow anyway. */
                    /* Note: no pivot rows or columns in the current front */
                    DEBUGm4 (("get_memory from umf_create_element, 1\n")) ;
                    return (UMF_get_memory (Numeric, Work, 0, r2, c2,do_Fcpos));
                }
                Col_tuples [col] = t2 ;
                tp2 = (Tuple *) (Memory + t2) ;
                if (t1)
                {
                    for (i = 0 ; i < len ; i++)
                    {
                        *tp2++ = *tp1++ ;
                    }
                    UMF_mem_free_tail_block (Numeric, t1) ;
                }
            }

            /* place the new (e,f) tuple in the element list of the column */
            Col_tlen [col]++ ;
            *tp2 = tuple ;
        }

        /* ------------------------------------------------------------------ */
        /* place (e,f) in the element list of each row */
        /* ------------------------------------------------------------------ */

        for (tuple.f = 0 ; tuple.f < fnrows ; tuple.f++)
        {
            row = Frows [tuple.f] ;
            ASSERT (row >= 0 && row < n_row) ;
            ASSERT (NON_PIVOTAL_ROW (row)) ;
            t1 = Row_tuples [row] ;
            DEBUG1 (("Placing on row:"ID" , tuples at "ID"\n",
                     row, Row_tuples [row])) ;

            size = 0 ;
            len = 0 ;
            if (t1)
            {
                p = Memory + t1 ;
                tp = (Tuple *) p ;
                size = GET_BLOCK_SIZE (p) ;
                len = Row_tlen [row] ;
                tp2 = tp + len ;
            }

            needunits = UNITS (Tuple, len + 1) ;
            DEBUG1 (("len: "ID" size: "ID" needunits: "ID"\n",
                     len, size, needunits)) ;

            if (needunits > size && t1)
            {
                /* prune the tuples */
                tp1 = tp ;
                tp2 = tp ;
                tpend = tp + len ;
                for ( ; tp < tpend ; tp++)
                {
                    e = tp->e ;
                    ASSERT (e > 0 && e <= Work->nel) ;
                    if (!E [e])
                    {
                        continue ;	/* element already deallocated */
                    }
                    f = tp->f ;
                    p = Memory + E [e] ;
                    ep = (Element *) p ;
                    p += UNITS (Element, 1) ;
                    Cols = (Int *) p ;
                    Rows = Cols + (ep->ncols) ;
                    if (Rows [f] == EMPTY) continue ;	/* already assembled */
                    ASSERT (row == Rows [f]) ;
                    *tp2++ = *tp ;	/* leave the tuple in the list */
                }
                len = tp2 - tp1 ;
                Row_tlen [row] = len ;
                needunits = UNITS (Tuple, len + 1) ;
            }

            if (needunits > size)
            {
                /* no room exists - reallocate elsewhere */
                DEBUG1 (("REALLOCATE Row: "ID", size "ID" to "ID"\n",
                         row, size, 2*needunits)) ;

#ifndef NDEBUG
                UMF_allocfail = FALSE ;
                if (UMF_gprob > 0)  /* a double relop, but ignore NaN case */
                {
                    double rrr = ((double) (rand ( ))) /
                                 (((double) RAND_MAX) + 1) ;
                    DEBUG1 (("Check random %e %e\n", rrr, UMF_gprob)) ;
                    UMF_allocfail = rrr < UMF_gprob ;
                    if (UMF_allocfail) DEBUGm2 (("Random gar. (row tuple)\n")) ;
                }
#endif

                needunits = MIN (2*needunits, (Int) UNITS (Tuple, nn)) ;
                t2 = UMF_mem_alloc_tail_block (Numeric, needunits) ;
                if (!t2)
                {
                    /* :: get memory in umf_create_element (2) :: */
                    /* get memory, reconstruct all tuple lists, and return */
                    /* Compact the current front if it needs to grow anyway. */
                    /* Note: no pivot rows or columns in the current front */
                    DEBUGm4 (("get_memory from umf_create_element, 2\n")) ;
                    return (UMF_get_memory (Numeric, Work, 0, r2, c2,do_Fcpos));
                }
                Row_tuples [row] = t2 ;
                tp2 = (Tuple *) (Memory + t2) ;
                if (t1)
                {
                    for (i = 0 ; i < len ; i++)
                    {
                        *tp2++ = *tp1++ ;
                    }
                    UMF_mem_free_tail_block (Numeric, t1) ;
                }
            }

            /* place the new (e,f) tuple in the element list of the row */
            Row_tlen [row]++ ;
            *tp2 = tuple ;
        }

    }

    /* ---------------------------------------------------------------------- */

#ifndef NDEBUG
    DEBUG1 (("Done extending\nFINAL: element row pattern: len="ID"\n", fncols));
    for (j = 0 ; j < fncols ; j++) DEBUG1 ((""ID"\n", Fcols [j])) ;
    DEBUG1 (("FINAL: element col pattern:  len="ID"\n", fnrows)) ;
    for (j = 0 ; j < fnrows ; j++) DEBUG1 ((""ID"\n", Frows [j])) ;
    for (j = 0 ; j < fncols ; j++)
    {
        col = Fcols [j] ;
        ASSERT (col >= 0 && col < n_col) ;
        UMF_dump_rowcol (1, Numeric, Work, col, !Symbolic->fixQ) ;
    }
    for (j = 0 ; j < fnrows ; j++)
    {
        row = Frows [j] ;
        ASSERT (row >= 0 && row < n_row) ;
        UMF_dump_rowcol (0, Numeric, Work, row, TRUE) ;
    }
    if (n_row < 1000 && n_col < 1000)
    {
        UMF_dump_memory (Numeric) ;
    }
    DEBUG1 (("New element, after filling with stuff: "ID"\n", e)) ;
    UMF_dump_element (Numeric, Work, e, TRUE) ;
    if (nn < 1000)
    {
        DEBUG4 (("Matrix dump, after New element: "ID"\n", e)) ;
        UMF_dump_matrix (Numeric, Work, TRUE) ;
    }
    DEBUG3 (("FRONTAL WRAPUP DONE\n")) ;
#endif

    return (TRUE) ;
}